Reference - What does this error mean in PHP

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What is this  This is a number of answers about warnings  errors  and notices you might encounter while programming PHP and have no clue how to fix them  This is also a Community Wiki  so everyone is invited to participate adding to and maintaining this list  Why is this  Questions like  quot Headers already sent quot  or  quot Calling a member of a non-object quot  pop up frequently on Stack Overflow  The root cause of those questions is always the same  So the answers to those questions typically repeat them and then show the OP which line to change in their particular case  These answers do not add any value to the site because they only apply to the OP s particular code  Other users having the same error cannot easily read the solution out of it because they are too localized  That is sad because once you understood the root cause  fixing the error is trivial  Hence  this list tries to explain the solution in a general way to apply  What should I do here  If your question has been marked as a duplicate of this one  please find your error message below and apply the fix to your code  The answers usually contain further links to investigate in case it shouldn t be clear from the general answer alone  If you want to contribute  please add your  quot favorite quot  error message  warning or notice  one per answer  a short description what it means  even if it is only highlighting terms to their manual page   a possible solution or debugging approach and a listing of existing Q amp A that are of value  Also  feel free to improve any existing answers  The List  Nothing is seen  The page is empty and white   also known as White Page Screen Of Death  Code doesn t run what looks like parts of my PHP code are output Warning  Cannot modify header information - headers already sent Warning  mysql fetch array   expects parameter 1 to be resource  boolean given a k a  Warning  mysql fetch array    supplied argument is not a valid MySQL result resource Warning   function  expects parameter 1 to be resource  boolean given Warning   function   failed to open stream   reason  Warning  open basedir restriction in effect Warning  Division by zero Warning  Illegal string offset  XXX  Warning  count    Parameter must be an array or an object that implements Countable Parse error  syntax error  unexpected     Parse error  syntax error  unexpected T XXX Parse error   syntax error  unexpected T ENCAPSED AND WHITESPACE Parse error  syntax error  unexpected T PAAMAYIM NEKUDOTAYIM Parse error  syntax error  unexpected  require once   T REQUIRE ONCE   expecting function  T FUNCTION  Parse error  syntax error  unexpected T VARIABLE Fatal error  Allowed memory size of XXX bytes exhausted  tried to allocate XXX bytes  Fatal error  Call to a member function     on a non-object or null Fatal Error  Call to Undefined function XXX Fatal Error  Cannot redeclare XXX Fatal error  Can t use function return value in write context Fatal error  Declaration of AAA  BBB   must be compatible with that of CCC  BBB    Fatal error  Using  this when not in object context Fatal error  Object of class Closure could not be converted to string Fatal error  Undefined class constant Notice  Array to string conversion Notice  Trying to get property of non-object error Notice  Undefined variable or property Notice  Undefined Index Notice  Undefined offset XXX  Reference  Notice  Uninitialized string offset  XXX Notice  Use of undefined constant XXX - assumed  XXX  MySQL  You have an error in your SQL syntax  check the manual that corresponds to your MySQL server version for the right syntax to use near     at line     Strict Standards  Non-static method   lt class gt    lt method gt   should not be called statically Warning  function expects parameter X to be boolean string integer HTTP Error 500 - Internal server error Deprecated  Arrays and strings offset access syntax with curly braces is deprecated  Also  see   Reference - What does this symbol mean in PHP

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Fatal error  Object of class Closure could not be converted to a string  It means that you are not executing your anonymous function  or a closure     An error will be thrown for this example using arrow functions   echo  fn   fn  x   42    gt   x    Or for any anonymous function  echo function  x   42    return  x       To resolve this error you need to execute the closure    echo  fn    fn  x   42    gt   x  30      take notice of the 2 sets of brackets  echo  function  x   42    return  x     30     This kind of syntax is called IIFE and it was added in PHP 7

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Parse error  syntax error  unexpected      This error comes in two variatians   Variation 1   arr    1  2  3     This array initializer syntax was only introduced in PHP 5 4  it will raise a parser error on versions before that  If possible  upgrade your installation or use the old syntax    arr   array 1  2  3     See also this example from the manual   Variation 2   suffix   explode       foo bar   1     Array dereferencing function results was also introduced in PHP 5 4  If it s not possible to upgrade you need to use a  temporary  variable    parts   explode       foo bar     suffix    parts 1     See also this example from the manual

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Warning  count    Parameter must be an array or an object that implements Countable Self-explanatory  the parameter passed to the count   function has to be something that is countable  usually an array  The likely problem is that a scalar value such as a string or integer was passed  or an object that doesn t implement the Countable interface  Using var dump   on the variable in question can show whether or not this is the case

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Notice  Use of undefined constant XXX - assumed  XXX   or  in PHP 7 2 or later   Warning  Use of undefined constant XXX - assumed  XXX   this will throw an Error in a future version of PHP   This notice occurs when a token is used in the code and appears to be a constant  but a constant by that name is not defined   One of the most common causes of this notice is a failure to quote a string used as an associative array key   For example      Wrong echo  array key       Right echo  array  key      Another common cause is a missing    dollar  sign in front of a variable name      Wrong echo varName      Right echo  varName    Or perhaps you have misspelled some other constant or keyword      Wrong  foo   fasle      Right  foo   false    It can also be a sign that a needed PHP extension or library is missing when you try to access a constant defined by that library   Related Questions    What does the PHP error message    Notice  Use of undefined constant    mean

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Notice  Array to string conversion  This simply happens if you try to treat an array as a string    arr   array  foo    bar     echo  arr      Notice  Array to string conversion  str    Something       arr      Notice  Array to string conversion   An array cannot simply be echo d or concatenated with a string  because the result is not well defined  PHP will use the string  Array  in place of the array  and trigger the notice to point out that that s probably not what was intended and that you should be checking your code here  You probably want something like this instead   echo  arr 0       displays foo  str    Something     join        arr     displays Something  foo  bar   Or loop the array   foreach  arr as  key   gt   value        echo  array  key    value          displays first  array 0   foo        displays next   array 1   bar     If this notice appears somewhere you don t expect  it means a variable which you thought is a string is actually an array  That means you have a bug in your code which makes this variable an array instead of the string you expect

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Notice  Uninitialized string offset     As the name indicates  such type of error occurs  when you are most likely trying to iterate over or find a value from an array with a non-existing key    Consider you  are trying to show every letter from  string    string    ABCD    for   i 0   len   strlen  string    i  lt    len   i         echo   string  i   n        The above example will generate  online demo    A B C D Notice  Uninitialized string offset  4 in XXX on line X   And  as soon as the script finishes echoing D you ll get the error  because inside the for   loop  you have told PHP to show you the from first to fifth string character from  ABCD  Which  exists  but since the loop starts to count from 0 and echoes D by the time it reaches to 4  it will throw an offset error    Similar Errors    Illegal string offset  option 1

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Warning  mysql fetch array   expects parameter 1 to be resource  boolean given  First and foremost      Please  don t use mysql   functions in new code  They are no longer maintained and are officially deprecated  See the red box  Learn about prepared statements instead  and use PDO or MySQLi - this article will help you decide which  If you choose PDO  here is a good tutorial      This happens when you try to fetch data from the result of mysql query but the query failed   This is a warning and won t stop the script  but will make your program wrong   You need to check the result returned by mysql query by    res   mysql query  sql   if    res       die mysql error          after checking  do the fetch   Related Questions    mysql fetch array   expects parameter 1 to be resource  boolean given in select All  mysql fetch array   expects parameter 1 to be resource  boolean given  Questions on Stackoverflow   Related Errors    Warning   function  expects parameter 1 to be resource  boolean given   Other mysql  functions that also expect a MySQL result resource as a parameter will produce the same error for the same reason

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Code doesn t run what looks like parts of my PHP code are output  If you see no result from your PHP code whatsoever and or you are seeing parts of your literal PHP source code output in the webpage  you can be pretty sure that your PHP isn t actually getting executed  If you use View Source in your browser  you re probably seeing the whole PHP source code file as is  Since PHP code is embedded in  lt  php   gt  tags  the browser will try to interpret those as HTML tags and the result may look somewhat confused   To actually run your PHP scripts  you need    a web server which executes your script to set the file extension to  php  otherwise the web server won t interpret it as such  to access your  php file via the web server     Unless you reconfigure it  everything can be configured   This last one is particularly important  Just double clicking the file will likely open it in your browser using an address such as   file   C  path to my file php   This is completely bypassing any web server you may have running and the file is not getting interpreted  You need to visit the URL of the file on your web server  likely something like   http   localhost my file php   You may also want to check whether you re using short open tags  lt   instead of  lt  php and your PHP configuration has turned short open tags off   Also see PHP code is not being executed  instead code shows on the page

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Fatal error  Using  this when not in object context   this is a special variable in PHP which can not be assigned  If it is accessed in a context where it does not exist  this fatal error is given   This error can occur    If a non-static method is called statically  Example   class Foo      protected  var     public function   construct  var            this- gt var    var           public static function bar                              echo  this- gt var                            Foo  bar      How to fix  review your code again   this can only be used in an object context  and should never be used in a static method  Also  a static method should not access the non-static property  Use self   static property to access the static property  If code from a class method has been copied over into a normal function or just the global scope and keeping the  this special variable  How to fix  Review the code and replace  this with a different substitution variable    Related Questions    Call non-static method as static  PHP Fatal error  Using  this when not in object context Copy over code  Fatal error  Using  this when not in object context All  Using  this when not in object context  Questions on Stackoverflow

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Fatal error   TraitA  and  TraitB  define the same property    x   in the composition of  ClassC   Occurs when a class attempts to use multiple Traits  where two or more of those Traits have defined a property by the same name  and with the property having differing initial values   Example    lt  php trait TraitA       public  x    a     trait TraitB       public  x    b     class ClassC       use TraitA  TraitB      Problematic  While it s possible to resolve conflicts between competing methods  there is currently no syntax that would resolve a conflict between two competing properties  The only solution at this time is to refactor  i e   avoid a conflict between property names that produces a fatal error     Related Questions    PHP Traits  How to resolve a property name conflict  Traits - property conflict with parent class

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Fatal error  Allowed memory size of XXX bytes exhausted  tried to allocate XXX bytes   There is not enough memory to run your script  PHP has reached the memory limit and stops executing it  This error is fatal  the script stops  The value of the memory limit can be configured either in the php ini file or by using ini set  memory limit    128 M    in the script  which will overwrite the value defined in php ini   The purpose of the memory limit is to prevent a single PHP script from gobbling up all the available memory and bringing the whole web server down   The first thing to do is to minimise the amount of memory your script needs  For instance  if you re reading a large file into a variable or are fetching many records from a database and are storing them all in an array  that may use a lot of memory  Change your code to instead read the file line by line or fetch database records one at a time without storing them all in memory  This does require a bit of a conceptual awareness of what s going on behind the scenes and when data is stored in memory vs  elsewhere   If this error occurred when your script was not doing memory-intensive work  you need to check your code to see whether there is a memory leak  The memory get usage function is your friend   Related Questions    All  Fatal error  Allowed memory size of XXX bytes exhausted  Questions on Stackoverflow

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Parse error  syntax error  unexpected T VARIABLE  Possible scenario  I can t seem to find where my code has gone wrong  Here is my full error      Parse error  syntax error  unexpected T VARIABLE on line x   What I am trying    sql    SELECT   FROM dealer WHERE id    id        Answer  Parse error  A problem with the syntax of your program  such as leaving a semicolon off of the end of a statement or  like the case above  missing the   operator  The interpreter stops running your program when it encounters a parse error   In simple words this is a syntax error  meaning that there is something in your code stopping it from being parsed correctly and therefore running   What you should do is check carefully at the lines around where the error is for any simple mistakes   That error message means that in line x of the file  the PHP interpreter was expecting to see an open parenthesis but instead  it encountered something called T VARIABLE  That T VARIABLE thing is called a token  It s the PHP interpreter s way of expressing different fundamental parts of programs  When the interpreter reads in a program  it translates what you ve written into a list of tokens  Wherever you put a variable in your program  there is aT VARIABLE token in the interpreter s list   Good read  List of Parser Tokens  So make sure you enable at least E PARSE in your php ini  Parse errors should not exist in production scripts   I always recommended to add the following statement  while coding   error reporting E ALL     PHP error reporting   Also  a good idea to use an IDE which will let you know parse errors while typing  You can use    NetBeans  a fine piece of beauty  free software   the best in my opinion  PhpStorm  uncle Gordon love this  P  paid plan  contains proprietary and free software  Eclipse  beauty and the beast  free software    Related Questions    Reference  PHP Parse Syntax Errors  and How to solve them

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Nothing is seen  The page is empty and white   Also known as the White Page Of Death or White Screen Of Death  This happens when error reporting is turned off and a fatal error  often syntax error  occurred   If you have error logging enabled  you will find the concrete error message in your error log  This will usually be in a file called  php errors log   either in a central location  e g   var log apache2 on many Linux environments  or in the directory of the script itself  sometimes used in a shared hosting environment    Sometimes it might be more straightforward to temporarily enable the display of errors  The white page will then display the error message  Take care because these errors are visible  to everybody visiting the website   This can be easily done by adding at the top of the script the following PHP code   ini set  display errors   1   error reporting  0     The code will turn on the display of errors and set reporting to the highest level   Since the ini set   is executed at runtime it has no effects on parsing syntax errors  Those errors will appear in the log  If you want to display them in the output as well  e g  in a browser  you have to set the display startup errors directive to true  Do this either in the php ini or in a  htaccess or by any other method that affects the configuration before runtime   You can use the same methods to set the log errors and error log directives to choose your own log file location   Looking in the log or using the display  you will get a much better error message and the line of code where your script comes to halt   Related questions    PHP s white screen of death White screen of death  PHP Does Not Display Error Messages PHP emitting 500 on errors - where is this documented  How to get useful error messages in PHP  All PHP  White Page of Death  Questions on Stackoverflow   Related errors    Parse error  syntax error  unexpected T XXX Fatal error  Call to a member function     on a non-object Code doesn t run what looks like parts of my PHP code are output

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MySQL  You have an error in your SQL syntax  check the manual that corresponds to your MySQL server version for the right syntax to use near     at line      This error is often caused because you forgot to properly escape the data passed to a MySQL query   An example of what not to do  the  Bad Idea      query    UPDATE  posts  SET my text     POST  text     WHERE id    GET  id      mysqli query  db   query     This code could be included in a page with a form to submit  with an URL such as http   example com edit php id 10  to edit the post n  10   What will happen if the submitted text contains single quotes   query will end up with    query    UPDATE  posts  SET my text  I m a PHP newbie  WHERE id 10     And when this query is sent to MySQL  it will complain that the syntax is wrong  because there is an extra single quote in the middle   To avoid such errors  you MUST always escape the data before use in a query   Escaping data before use in a SQL query is also very important because if you don t  your script will be open to SQL injections  An SQL injection may cause alteration  loss or modification of a record  a table or an entire database  This is a very serious security issue   Documentation    How can I prevent SQL injection in PHP  mysql real escape string     mysqli real escape string     How does the SQL injection from the  quot Bobby Tables quot  XKCD comic work  SQL injection that gets around mysql real escape string

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Strict Standards  Non-static method   lt class    lt method   should not be called statically  Occurs when you try to call a non-static method on a class as it was static  and you also have the E STRICT flag in your error reporting   settings   Example    class HTML      public function br           echo   lt br gt             HTML  br   or  html  br    You can actually avoid this error by not adding E STRICT to error reporting    eg  error reporting E ALL  amp   E STRICT     since as for PHP 5 4 0 and above  E STRICT is included in E ALL  ref   But that is not adviceable  The solution is to define your intended static function as actual static    public static function br       echo   lt br gt        or call the function conventionally     html   new HTML     html- gt br        Related questions       How can I solve  Non-static method xxx xxx   should not be called statically in PHP 5 4

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Fatal error  Call to a member function     on a non-object  Happens with code similar to xyz- gt method   where xyz is not an object and therefore that method can not be called   This is a fatal error which will stop the script  forward compatibility notice  It will become a catchable error starting with PHP 7    Most often this is a sign that the code has missing checks for error conditions  Validate that an object is actually an object before calling its methods   A typical example would be         some code using PDO  statement    pdo- gt prepare  invalid query          statement- gt execute         In the example above  the query cannot be prepared and prepare   will assign false to  statement  Trying to call the execute   method will then result in the Fatal Error because false is a  non-object  because the value is a boolean   Figure out why your function returned a boolean instead of an object  For example  check the  pdo object for the last error that occurred  Details on how to debug this will depend on how errors are handled for the particular function object class in question   If even the - gt prepare is failing then your  pdo database handle object didn t get passed into the current scope  Find where it got defined  Then pass it as a parameter  store it as property  or share it via the global scope   Another problem may be conditionally creating an object and then trying to call a method outside that conditional block  For example  if   someCondition         myObj   new MyObj              myObj- gt someMethod      By attempting to execute the method outside the conditional block  your object may not be defined   Related Questions    Call to a member function on a non-object List all PHP  Fatal error  Call to a member function     on a non-object  Questions on Stackoverflow

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Notice  Undefined Index  Happens when you try to access an array by a key that does not exist in the array    A typical example of an Undefined Index notice would be  demo    data   array  foo    gt   42    bar    echo  data  spinach    echo  data 1     Both spinach and 1 do not exist in the array  causing an E NOTICE to be triggered   The solution is to make sure the index or offset exists prior to accessing that index  This may mean that you need to fix a bug in your program to ensure that those indexes do exist when you expect them to  Or it may mean that you need to test whether the indexes exist using array key exists or isset    data   array  foo    gt   42    bar    if  array key exists  spinach    data         echo  data  spinach      else       echo  No key spinach in the array       If you have code like    lt  php echo   POST  message      gt   lt form method  post  action    gt       lt input type  text  name  message  gt            then   POST  message   will not be set when this page is first loaded and you will get the above error  Only when the form is submitted and this code is run a second time will the array index exist  You typically check for this with   if    POST          if the   POST array is not empty    or if    SERVER  REQUEST METHOD       POST          page was requested with POST   Related Questions    Reference     Notice  Undefined variable    and    Notice  Undefined index    All PHP  Notice  Undefined Index  Questions on Stackoverflow http   php net arrays

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Parse error  syntax error  unexpected T XXX  Happens when you have T XXX token in unexpected place  unbalanced  superfluous  parentheses  use of short tag without activating it in php ini  and many more   Related Questions    Reference  PHP Parse Syntax Errors  and How to solve them  Parse Error  syntax error  unexpected     Parse error  Syntax error  unexpected end of file in my PHP code Parse error  syntax error  unexpected   lt   in - Fix  Parse error  syntax error  unexpected       For further help see    http   phpcodechecker com  - Which does provide some more helpful explanations on your syntax woes

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Warning   function  expects parameter 1 to be resource  boolean given  A more general variation of Warning  mysql fetch array   expects parameter 1 to be resource  boolean given  Resources are a type in PHP  like strings  integers or objects   A resource is an opaque blob with no inherently meaningful value of its own  A resource is specific to and defined by a certain set of PHP functions or extension  For instance  the Mysql extension defines two resource types   There are two resource types used in the MySQL module  The first one is the link identifier for a database connection  the second a resource which holds the result of a query   The cURL extension defines another two resource types       a cURL handle and a cURL multi handle   When var dumped  the values look like this   resource   curl init    var dump  resource    resource 1  of type  curl   That s all most resources are  a numeric identifier   1   of a certain type   curl    You carry these resources around and pass them to different functions for which such a resource means something  Typically these functions allocate certain data in the background and a resource is just a reference which they use to keep track of this data internally   The  quot     expects parameter 1 to be resource  boolean given quot  error is typically the result of an unchecked operation that was supposed to create a resource  but returned false instead  For instance  the fopen function has this description   Return Values Returns a file pointer resource on success  or FALSE on error   So in this code   fp will either be a resource x  of type  stream  or false   fp   fopen        If you do not check whether the fopen operation succeed or failed and hence whether  fp is a valid resource or false and pass  fp to another function which expects a resource  you may get the above error   fp     fopen        data   fread  fp  1024    Warning  fread   expects parameter 1 to be resource  boolean given  You always need to error check the return value of functions which are trying to allocate a resource and may fail   fp   fopen        if    fp        trigger error  Failed to allocate resource        exit      data   fread  fp  1024    Related Errors   Warning  mysql fetch array   expects parameter 1 to be resource  boolean given

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Fatal error  Can t use function return value in write context  This usually happens when using a function directly with empty   Example   if  empty is null null        echo  empty       This is because empty is a language construct and not a function  it cannot be called with an expression as its argument in PHP versions before 5 5   Prior to PHP 5 5  the argument to empty   must be a variable  but an arbitrary expression  such as a return value of a function  is permissible in PHP 5 5    empty  despite its name  does not actually check if a variable is  empty   Instead  it checks if a variable doesn t exist  or    false  Expressions  like is null null  in the example  will always be deemed to exist  so here empty is only checking if it is equal to false  You could replace empty   here with    e g  if   is null null    or explicitly compare to false  e g  if  is null null     false    Related Questions    Fatal error  Can t use function the return value

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Warning  Division by zero  The warning message  Division by zero  is one of the most commonly asked questions among new PHP developers   This error will not cause an exception  therefore  some developers will occasionally suppress the warning by adding the error suppression operator   before the expression   For example    value     2   0     But  like with any warning  the best approach would be to track down the cause of the warning and resolve it   The cause of the warning is going to come from any instance where you attempt to divide by 0  a variable equal to 0  or a variable which has not been assigned  because NULL    0  because the result will be  undefined    To correct this warning  you should rewrite your expression to check that the value is not 0  if it is  do something else   If the value is zero you either should not divide  or you should change the value to 1 and then divide so the division results in the equivalent of having divided only by the additional variable   if    var1    0        check if var1 equals zero      var1   1     var1 equaled zero so change var1 to equal one instead      var3     var2    var1      divide var1 var2 ie  1 1   else        var3     var2    var1      if var1 does not equal zero  divide     Related Questions    warning  division by zero Warning  Division By Zero Working on PHP and MySQL Division by zero error in WordPress Theme How to suppress the    Division by zero    error How to catch a division by zero

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Warning  Illegal string offset  XXX   This happens when you try to access an array element with the square bracket syntax  but you re doing this on a string  and not on an array  so the operation clearly doesn t make sense   Example    var    test   echo  var  a key      If you think the variable should be an array  see where it comes from and fix the problem there

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Warning  open basedir restriction in effect  This warning can appear with various functions that are related to file and directory access  It warns about a configuration issue   When it appears  it means that access has been forbidden to some files   The warning itself does not break anything  but most often a script does not properly work if file-access is prevented    The fix is normally to change the PHP configuration  the related setting is called open basedir   Sometimes the wrong file or directory names are used  the fix is then to use the right ones   Related Questions    open basedir restriction in effect  File    is not within the allowed path s   All PHP  Warning  open basedir restriction in effect  Querstions on Stackoverflow

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Warning  function   expects parameter X to be boolean  or integer  string  etc  If the wrong type of parameter is passed to a function     and PHP cannot convert it automatically     a warning is thrown  This warning identifies which parameter is the problem  and what data type is expected  The solution  change the indicated parameter to the correct data type   For example this code  echo substr   quot foo quot    23    Results in this output   PHP Warning   substr   expects parameter 1 to be string  array given

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Fatal error  Call to undefined function XXX  Happens when you try to call a function that is not defined yet  Common causes include missing extensions and includes  conditional function declaration  function in a function declaration or simple typos   Example 1 - Conditional Function Declaration   someCondition   false  if   someCondition     true        function fn             return 1          echo fn       triggers error   In this case  fn   will never be declared because  someCondition is not true    Example 2 - Function in Function Declaration  function createFn          function fn             return 1          echo fn       triggers error   In this case  fn will only be declared once createFn   gets called  Note that subsequent calls to createFn   will trigger an error about Redeclaration of an Existing function   You may also see this for a PHP built-in function  Try searching for the function in the official manual  and check what  extension   PHP module  it belongs to  and what versions of PHP support it   In case of a missing extension  install that extension and enable it in php ini  Refer to the Installation Instructions in the PHP Manual for the extension your function appears in  You may also be able to enable or install the extension using your package manager  e g  apt in Debian or Ubuntu  yum in Red Hat or CentOS   or a control panel in a shared hosting environment   If the function was introduced in a newer version of PHP from what you are using  you may find links to alternative implementations in the manual or its comment section  If it has been removed from PHP  look for information about why  as it may no longer be necessary   In case of missing includes  make sure to include the file declaring the function before calling the function    In case of typos  fix the typo   Related Questions    https   stackoverflow com search q Fatal error 3A Call to undefined function

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Warning   function   failed to open stream   reason   It happens when you call a file usually by include  require or fopen and PHP couldn t find the file or have not enough permission to load the file   This can happen for a variety of reasons     the file path is wrong the file path is relative include path is wrong permissions are too restrictive SELinux is in force and many more       One common mistake is to not use an absolute path  This can be easily solved by using a full path or magic constants like   DIR   or  dirname   FILE      include   DIR       inc globals inc php     or   require dirname   FILE        inc globals inc php     Ensuring the right path is used is one step in troubleshooting these issues  this can also be related to non-existing files  rights of the filesystem preventing access or open basedir restrictions by PHP itself   The best way to solve this problem quickly is to follow the troubleshooting checklist below   Related Questions    Troubleshooting checklist  Failed to open stream   Related Errors    Warning  open basedir restriction in effect

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Parse error  syntax error  unexpected T PAAMAYIM NEKUDOTAYIM  The scope resolution operator is also called  Paamayim Nekudotayim  from the Hebrew                   which means  double colon    This error typically happens if you inadvertently put    in your code   Related Questions    Reference  PHP Parse Syntax Errors  and How to solve them  What do two colons mean in PHP  What  39 s the difference between     double colon  and - gt   arrow  in PHP  Unexpected T PAAMAYIM NEKUDOTAYIM  expecting T NS Separator   Documentation    Scope Resolution Operator

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HTTP Error 500 - Internal server error  The HTTP status code 500 and the typical Apache or browser warning is a very broad message  It s not the actual error  To figure out if it s a webserver misconfiguration   htaccess  or a PHP fatal error  you have to look at the error log     You can typically find the webservers log under     var log apache2 on Linux servers  often used for local and virtual hosts   var www  user12345  logs or similar on shared hosting plans   Usually there s a logs  directory alongside each htdocs  folder  C  xampp apache logs error log for WAMP XAMPP distributions of Apache PHP  Alternatively just use a file search feature to locate anything called  error log   Or look into your Apache httpd conf and its ErrorLog directive   var log nginx nginx error log for NGINX  C  inetpub logs LogFiles for IIS  Luckily this is uncommon still  but journalctl -r -u apache2 service could also hold parts of the log on Linux setups    It s a text file  Search for the entry most closely matching the error time  and use the significant part of the error message  from  PHP Error       until  in line      for further googling       Mon 22 10    error   pid 12345   client 127 0 0 1  FastCGI  server   fcgi p73  stderr  PHP message PHP Error  Unfiltered inputvariable   JSON  pokestop lng   in filyfile php on line 845   For FPM setups you will often just see fatal PHP errors here  Whereas older mod php  shared hosting  configurations often mix in warnings and notices  which usually are also worth inspecting    If not configured to use the system or Apache logging mechanism  you may also want to look at PHP s error log  Generally it s simpler to leave the defaults and just enable error display   error reporting to reveal the concrete error  The HTTP 500 catch-all page after all is just a variation of PHP s white screen of death   See also    500 Internal Server Error for php file not for html How can I make PHP display the error instead of giving me 500 Internal Server Error How can I display and log PHP errors on IIS7  How to Fix the 500 Internal Server Error in WordPress

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Fatal error  Cannot redeclare class  class name   Fatal error  Cannot redeclare  function name   This means you re either using the same function class name twice and need to rename one of them   or it is because you have used require or include where you should be using require once or include once   When a class or a function is declared in PHP  it is immutable  and cannot later be declared with a new value   Consider the following code   class php   lt  php  class MyClass       public function doSomething                    do stuff here           index php   lt  php  function do stuff        require  class php       obj   new MyClass      obj- gt doSomething       do stuff    do stuff      The second call to do stuff   will produce the error above  By changing require to require once  we can be certain that the file that contains the definition of MyClass will only be loaded once  and the error will be avoided

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Notice  Trying to get property of non-object error  Happens when you try to access a property of an object while there is no object   A typical example for a non-object notice would be   users   json decode     name    hakre       echo  users- gt name    Notice  Trying to get property of non-object   In this case   users is an array  so not an object  and it does not have any properties   This is similar to accessing a non-existing index or key of an array  see Notice  Undefined Index    This example is much simplified  Most often such a notice signals an unchecked return value  e g  when a library returns NULL if an object does not exists or just an unexpected non-object value  e g  in an Xpath result  JSON structures with unexpected format  XML with unexpected format etc   but the code does not check for such a condition   As those non-objects are often processed further on  often a fatal-error happens next on calling an object method on a non-object  see  Fatal error  Call to a member function     on a non-object  halting the script   It can be easily prevented by checking for error conditions and or that a variable matches an expectation  Here such a notice with a DOMXPath example    result     xpath- gt query       id  detail-sections   div 1      divText    result- gt item 0 - gt nodeValue    Notice  Trying to get property of non-object   The problem is accessing the nodeValue property  field  of the first item while it has not been checked if it exists or not in the  result collection  Instead it pays to make the code more explicit by assigning variables to the objects the code operates on    result     xpath- gt query       id  detail-sections   div 1      div        result- gt item 0    divText    - -   if  is object  div          divText    div- gt nodeValue    echo  divText    Related errors    Notice  Undefined Index Fatal error  Call to a member function     on a non-object

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Parse error   syntax error  unexpected T ENCAPSED AND WHITESPACE  This error is most often encountered when attempting to reference an array value with a quoted key for interpolation inside a double-quoted string when the entire complex variable construct is not enclosed in      The error case   This will result in Unexpected T ENCAPSED AND WHITESPACE   echo  This is a double-quoted string with a quoted array key in  array  key       ---------------------------------------------------------------------        Possible fixes   In a double-quoted string  PHP will permit array key strings to be used unquoted  and will not issue an E NOTICE   So the above could be written as   echo  This is a double-quoted string with an un-quoted array key in  array key      ------------------------------------------------------------------------        The entire complex array variable and key s  can be enclosed in     in which case they should be quoted to avoid an E NOTICE   The PHP documentation recommends this syntax for complex variables   echo  This is a double-quoted string with a quoted array key in   array  key        --------------------------------------------------------------                   Or a complex array property of an object  echo  This is a a double-quoted string with a complex   object- gt property- gt array  key        Of course  the alternative to any of the above is to concatenate the array variable in instead of interpolating it   echo  This is a double-quoted string with an array variable    array  key       concatenated inside      ----------------------------------------------------------                        For reference  see the section on Variable Parsing in the PHP Strings manual page

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Warning  Cannot modify header information - headers already sent  Happens when your script tries to send an HTTP header to the client but there already was output before  which resulted in headers to be already sent to the client   This is an E WARNING and it will not stop the script   A typical example would be a template file like this    lt html gt       lt  php session start      gt       lt head gt  lt title gt My Page lt  title gt   lt  html gt        The session start   function will try to send headers with the session cookie to the client  But PHP already sent headers when it wrote the  lt html gt  element to the output stream  You d have to move the session start   to the top   You can solve this by going through the lines before the code triggering the Warning and check where it outputs  Move any header sending code before that code    An often overlooked output is new lines after PHP s closing   gt   It is considered a standard practice to omit   gt  when it is the last thing in the file  Likewise  another common cause for this warning is when the opening  lt  php has an empty space  line  or invisible character before it  causing the web server to send the headers and the whitespace newline thus when PHP starts parsing won t be able to submit any header   If your file has more than one  lt  php       gt  code block in it  you should not have any spaces in between them   Note  You might have multiple blocks if you had code that was automatically constructed   Also make sure you don t have any Byte Order Marks in your code  for example when the encoding of the script is UTF-8 with BOM   Related Questions    Headers already sent by PHP All PHP  Headers already sent  Questions on Stackoverflow Byte Order Mark What PHP Functions Create Output

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Warning  mysql connect    Access denied for user  name   host   This warning shows up when you connect to a MySQL MariaDB server with invalid or missing credentials  username password   So this is typically not a code problem  but a server configuration issue    See the manual page on mysql connect  localhost    user    pw   for examples  Check that you actually used a  username and  password      It s uncommon that you gain access using no password - which is what happened when the Warning  said  using password  NO   Only the local test server usually allows to connect with username root  no password  and the test database name  You can test if they re really correct using the command line client  mysql --user  username  --password  password  testdb Username and password are case-sensitive and whitespace is not ignored  If your password contains meta characters like    escape them  or put the password in single quotes  Most shared hosting providers predeclare mysql accounts in relation to the unix user account  sometimes just prefixes or extra numeric suffixes   See the docs for a pattern or documentation  and CPanel or whatever interface for setting a password  See the MySQL manual on Adding user accounts using the command line  When connected as admin user you can issue a query like   CREATE USER  username   localhost  IDENTIFIED BY  newpassword   Or use Adminer or WorkBench or any other graphical tool to create  check or correct account details  If you can t fix your credentials  then asking the internet to  please help  will have no effect  Only you and your hosting provider have permissions and sufficient access to diagnose and fix things   Verify that you could reach the database server  using the host name given by your provider   ping dbserver hoster example net   Check this from a SSH console directly on your webserver  Testing from your local development client to your shared hosting server is rarely meaningful  Often you just want the server name to be  localhost   which normally utilizes a local named socket when available  Othertimes you can try  127 0 0 1  as fallback  Should your MySQL MariaDB server listen on a different port  then use  servername 3306   If that fails  then there s a perhaps a firewall issue   Off-topic  not a programming question  No remote guess-helping possible    When using constants like e g  DB USER or DB PASSWORD  check that they re actually defined    If you get a  Warning  Access defined for  DB USER   host   and a  Notice  use of undefined constant  DB PASS    then that s your problem  Verify that your e g  xy db-config php was actually included and whatelse   Check for correctly set GRANT permissions    It s not sufficient to have a username password pair  Each MySQL MariaDB account can have an attached set of permissions  Those can restrict which databases you are allowed to connect to  from which client server the connection may originate from  and which queries are permitted  The  Access denied  warning thus may as well show up for mysql query calls  if you don t have permissions to SELECT from a specific table  or INSERT UPDATE  and more commonly DELETE anything  You can adapt account permissions when connected per command line client using the admin account with a query like   GRANT ALL ON yourdb   TO  username   localhost    If the warning shows up first with Warning  mysql query    Access denied for user     localhost  then you may have a php ini-preconfigured account password pair    Check that mysql default user  and mysql default password  have meaningful values  Oftentimes this is a provider-configuration  So contact their support for mismatches   Find the documentation of your shared hosting provider    e g  HostGator  GoDaddy  1and1  DigitalOcean  BlueHost  DreamHost  MediaTemple  ixWebhosting  lunarhosting  or just google yours    Else consult your webhosting provider through their support channels   Note that you may also have depleted the available connection pool  You ll get access denied warnings for too many concurrent connections   You have to investigate the setup  That s an off-topic server configuration issue  not a programming question   Your libmysql client version may not be compatible with the database server  Normally MySQL and MariaDB servers can be reached with PHPs compiled in driver  If you have a custom setup  or an outdated PHP version  and a much newer database server  or significantly outdated one - then the version mismatch may prevent connections   No  you have to investigate yourself  Nobody can guess your setup     More references    Serverfault  mysql access denied for  root   name of the computer  Warning  mysql connect    Access denied Warning  mysql select db   Access denied for user   39   39    39 localhost  39   using password  NO  Access denied for user   39 root  39    39 localhost  39  with PHPMyAdmin      Btw  you probably don t want to use mysql   functions anymore  Newcomers often migrate to mysqli  which however is just as tedious  Instead read up on PDO and prepared statements      db   new PDO  mysql host localhost dbname testdb    username    password

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Fatal error  Undefined class constant This error means that you have attempted to use a class constant that does not exist  Unlike other  quot undefined quot  notices and warnings  this is a fatal error and will stop the script immediately  The first thing to be checked should be typographic errors  Confirm the constant is defined in the class  and that it is called using the appropriate namespace  Confirm also that all appropriate files have been included to resolve the constant

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Notice  Undefined variable Happens when you try to use a variable that wasn t previously defined  A typical example would be foreach   items as  item           do something with item      counter       If you didn t define  counter before  the code above will trigger the notice  The correct way would be to set the variable before using it  even if it s just an empty string like  counter   0  foreach   items as  item           do something with item      counter       Similarly  a variable is not accessible outside its scope  for example when using anonymous functions   prefix    quot Blueberry quot    food     quot cake quot    quot cheese quot    quot pie quot     prefixedFood   array map function   food         Prefix is undefined   return  quot   prefix    food  quot       food    This should instead be passed using use  prefix    quot Blueberry quot    food     quot cake quot    quot cheese quot    quot pie quot     prefixedFood   array map function   food  use   prefix      return  quot   prefix    food  quot       food    Notice  Undefined property This error means much the same thing  but refers to a property of an object  Reusing the example above  this code would trigger the error because the counter property hasn t been set   obj   new stdclass   obj- gt property   2342  foreach   items as  item           do something with item      obj- gt counter       Related Questions   All PHP  quot Notice  Undefined Variable quot  Questions on Stackoverflow  quot Notice  Undefined variable quot    quot Notice  Undefined index quot   and  quot Notice  Undefined offset quot  using PHP Reference  What is variable scope  which variables are accessible from where and what are  quot undefined variable quot  errors

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Deprecated  Array and string offset access syntax with curly braces is deprecated String offsets and array elements could be accessed by curly braces    prior to PHP 7 4 0   string    abc   echo  string 0       a   array    1  2  3   echo  array 0       1  This has been deprecated since PHP 7 4 0 and generates a warning   Deprecated  Array and string offset access syntax with curly braces is deprecated  You must use square brackets    to access string offsets and array elements   string    abc   echo  string 0       a   array    1  2  3   echo  array 0       1  The RFC for this change links to a PHP script which attempts to fix this mechanically

[php] Reference - What does this error mean in PHP?

Fatal error: Object of class Closure could not be converted to a string

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