XMLHttpRequest status 0 responseText is empty

Question

Cannot get data with XMLHttpRequest  status 0 and responseText is empty     xmlhttp new XMLHttpRequest    xmlhttp open  GET   http   www w3schools com XML cd catalog xml   true   xmlhttp onreadystatechange function        if xmlhttp readyState  4      alert  status     xmlhttp status     xmlhttp send      It alerts  status 0    The same situation with the localhost request  cd catalog xml is saved as a local file    xmlhttp open  GET   http   localhost cd catalog xml   true     But with the localhost IP request   xmlhttp open  GET   http   127 0 0 1 cd catalog xml   true     and with the local file request   xmlhttp open  GET   cd catalog xml   true     everything is OK  status 200   What can cause the problem  status 0  with the online request   PS  Live HTTP Headers shows that everything is OK in all 4 cases      HTTP 1 1 200 OK   Content-Length  4742   PS2  Apache local web server on VMWare  host OS Win7  Guest OS Ubuntu  Network adapter     NAT   Browser     Firefox

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Alex Robinson already  and first  gives the correct answer to this issue  But to elaborate it a little more     You must add the HTTP response header   Access-Control-Allow-Origin     If you do this  the result is not just  might work   but  will work    NB What you need to add is an HTTP response header - so you can only do this on a server which you control  It will never be possible to directly fetch http   w3schools com XML cd catalog xml from its original URL using an XMLHttpRequest  as per OP s question   because that resource does not  at least  not as of 24 Apr 2015  include any such CORS header   http   en wikipedia org wiki Cross-origin resource sharing gives more info

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I had to add my current IP address  again  to the Atlas MongoDB whitelist and so got rid of the XMLHttpRequest status 0 error

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If the server responds to an OPTIONS method and to GET and POST  whichever of them you re using  with a header like   Access-Control-Allow-Origin      It might work OK  Seems to in FireFox 3 5 and rekonq 0 4 0  Apparently  with that header and the initial response to OPTIONS  the server is saying to the browser   Go ahead and let this cross-domain request go through

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I had faced a similar problem  Every thing was okay  the  readystate  was 4  but the  status  was 0  It was because I was using a Apache PHP portable server and my file in which I used the  XMLHttpRequest  object was a html file  I changed the file extension to php and the problem was solved

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I had the same problem  readyState was 4 and status 0   then I followed a different approach explained in this tutorial   https   spring io guides gs consuming-rest-jquery   He didn t use XMLHttpRequest at all  instead he used jquery   ajax   method    lt head gt       lt script src  https   ajax googleapis com ajax libs jquery 1 10 2 jquery min js  gt  lt  script gt       lt script src  hello js  gt  lt  script gt   lt  head gt    lt body gt       lt div gt           lt p class  greeting-id  gt The ID is  lt  p gt           lt p class  greeting-content  gt The content is  lt  p gt       lt  div gt   lt  body gt    and for the public hello js file  or you could insert it in the same HTML code directly      document  ready function             ajax           url   http   rest-service guides spring io greeting        then function data              greeting-id   append data id             greeting-content   append data content

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The cause of your problems is that you are trying to do a cross-domain call and it fails   If you re doing localhost development you can make cross-domain calls - I do it all the time    For Firefox  you have to enable it in your config settings  signed applets codebase principal support   true   Then add something like this to your XHR open code     if  isLocalHost         if  typeof netscape      undefined   amp  amp  typeof netscape security      undefined          netscape security PrivilegeManager enablePrivilege  UniversalBrowserRead                For IE  if I remember right  all you have to do is enable the browser s Security setting under  Miscellaneous  rarr  Access data sources across domains  to get it to work with ActiveX XHRs    IE8 and above also added cross-domain capabilities to the native XmlHttpRequest objects  but I haven t played with those yet

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A browser request  127 0 0 1 somefile html  arrives unchanged to the local webserver  while  localhost somefile html  may arrive as  0 0 0 0 0 0 0 1 somefile html  if IPv6 is supported  So the latter can be processed as going from a domain to another

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To see what the problem is  when you get the cryptic error 0 go to       More Tools   Developer Tools  Ctrl Shift I  in Chrome  on the page giving the error   Read the red text in the log to get the true error message  If there is too much in there  right-click and Clear Console  then do your last request again    My first problem was  I was passing in Authorization headers to my own cross-domain web service for the browser for the first time   I already had    Access-Control-Allow-Origin      But not   Access-Control-Allow-Methods  GET  POST  PUT  DELETE Access-Control-Allow-Headers  Authorization   in the response header of my web service   After I added that  my error zero was gone from my own web server  as well as when running the index html file locally without a web server  but was still giving errors in code pen   Back to       More Tools   Developer Tools while getting the error in codepen  and there is clearly explained  codepen uses https  so I cannot make calls to http  as the security is lower    I need to therefore host my web service on https   Knowing how to get the true error message - priceless

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I just had this issue because I used 0 0 0 0 as my server  changed it to localhost and it works

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Consider also the request timeout   Modern browser return readyState 4 and status 0 if too much time passes before the server response

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Alex Robinson and bmju provided valuable information to understand cross-origin issues  I wanted to add that you may need to make an explicit OPTIONS call in your client code before making the desired GET POST  e g  against a CORS OAuth service endpoint   Your browser library may not automatically handle the OPTIONS request  Gruber  this is one of the possible answers to your question

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Add setRequestHeader  Access-Control-Allow-Origin       to your server response

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status is 0 when your html file containing the script is opened in the browser via the file scheme  Make sure to place the files in your server  apache or tomcat whatever  and then open it via http protocol in the browser   i e  http   localhost myfile html  This is the solution

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My problem similar to this was solved by checking my html code  I was having an onclick handler in my form submit button to a method  like this   onclick  sendFalconRequestWithHeaders     This method in turn calls ajax just like yours  and does what I want  But not as expected  my browser was returning nothing   Learned From someone s hardwork   I have returned false in this handler  and solved  Let me mention that before arriving to this post  I have spent a whole 3-day weekend and a half day in office writing code implementing CORS filters  jetty config  other jersey and embedded jetty related stuff - just to fix this   revolving all my understanding around cross domain ajax requests and standards stuff  It was ridiculous how simple mistakes in javascript make you dumb   To be true  I have tried signed applets codebase principal support   true and written isLocalHost     if    may be this method needs to be implemented by us  firefox says there is no such  Now I have to clean my code to submit git patch cleanly  Thanks to that someone

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Actually make sure your button type is Button not Submit  that caused status conflict where I met recently

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Open javascript console  You ll see an error message there  In my case it was CORS

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Edit  Please read Malvolio s comments below as this answer s knowledge is outdated   You cannot do cross-domain XMLHttpRequests   The call to 127 0 0 1 works because your test page is located at 127 0 0 1  and the local test also works since  well    it s a local test   The other two tests fail because JavaScript cannot communicate with a distant server through XMLHttpRequest   You might instead consider either      XMLHttp-request your own server to fetch your remote XML content for you  php script  for example    Trying to use a service like GoogleAppEngine if you want to keep it full JavaScript    Hope that helps

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To answer the question of why http   127 0 0 1 cd catalog xml works while http   localhost cd catalog xml doesn t  Firefox is treating 127 0 0 1 and localhost as two different domains

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Here s another case in which status     0  specific to uploading   If you attach a  load  event handler to XHR upload  as suggested by MDN  scroll down to the upload part of  Monitoring progress    the XHR object will have status 0 and all the other properties will be empty strings  If you attach the  load  handler directly to the XHR object  as you would when downloading content  you should be fine  given you re not running off localhost    However  if you want to get good data in your  progress  event handlers  you need to attach a handler to XHR upload  not directly to the XHR object itself   I ve only tested this so far on Chrome OSX  so I m not sure how much of the problem here is MDN s documentation and how much is Chrome s implementation

[javascript] XMLHttpRequest status 0 (responseText is empty)

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