Hexadecimal value 0x00 is a invalid character

Question

I am generating an XML document from a StringBuilder  basically something like   string Format   lt text gt  lt row gt  0  lt  row gt  lt col gt  1  lt  col gt  lt textHeight gt  2  lt  textHeight gt  lt textWidth gt  3  lt  textWidth gt  lt data gt  4  lt  data gt  lt rotation gt  5  lt  rotation gt  lt  text gt    Later  something like   XmlDocument document   new XmlDocument    document LoadXml xml   XmlNodeList labelSetNodes   document GetElementsByTagName  labels    for  int index   0  index  lt  labelSetNodes Count  index            do something     All the data comes from a database  Recently I ve had a few issues with the error      Hexadecimal value 0x00 is a invalid character  line 1  position nnnnn   But its not consistent  Sometimes some  blank  data will work  The  faulty  data works on some PCs  but not others   In the database  the data is always a blank string  It is never  null  and in the XML file  it comes out as  lt  data gt  lt   data gt   i e  no character between opening and closing   but not sure if this can be relied on as I am pulling it from the  immediate  window is vis studio and pasting it into textpad    There is possibly differences in the versions of sql server  2008 is where it would fail  2005 would work  and collation too  Not sure if any of these are likely causes   But exactly the same code and data will sometimes fail  Any ideas where the problem lies

User · Answer

In my case  it took some digging  but found it   My Context  I m looking at exception error logs from the website using Elmah   Elmah returns the state of the server at the of time the exception  in the form of a large XML document   For our reporting engine I pretty-print the XML with XmlWriter   During a website attack  I noticed that some xmls weren t parsing and was receiving this      hexadecimal value 0x00  is an invalid character  exception   NON-RESOLUTION  I converted the document to a byte   and sanitized it of 0x00  but it found none   When I scanned the xml document  I found the following        lt form gt       lt item name  SomeField  gt      lt value      string  C  boot ini amp  x0  htm    gt    lt  item gt        There was the nul byte encoded as an html entity  amp  x0       RESOLUTION  To fix the encoding  I replaced the  amp  x0  value before loading it into my XmlDocument  because loading it will create the nul byte and it will be difficult to sanitize it from the object   Here s my entire process   XmlDocument xml   new XmlDocument    details Xml   details Xml Replace   amp  x0      0x00         in my case I want to see it  otherwise just replace with    xml LoadXml details Xml    string formattedXml   null      I have this in a helper function  but for this example I have put it in-line StringBuilder sb   new StringBuilder    XmlWriterSettings settings   new XmlWriterSettings       OmitXmlDeclaration   true      Indent   true      IndentChars     t       NewLineHandling   NewLineHandling None     using  XmlWriter writer   XmlWriter Create sb  settings         xml Save writer       formattedXml   sb ToString        LESSON LEARNED  sanitize for illegal bytes using the associated html entity  if your incoming data is html encoded on entry

User · Answer

Without your actual data or source  it will be hard for us to diagnose what is going wrong  However  I can make a few suggestions    Unicode NUL  0x00  is illegal in all versions of XML and validating parsers must reject input that contains it  Despite the above  real-world non-validated XML can contain any kind of garbage ill-formed bytes imaginable  XML 1 1 allows zero-width and nonprinting control characters  except NUL   so you cannot look at an XML 1 1 file in a text editor and tell what characters it contains    Given what you wrote  I suspect whatever converts the database data to XML is broken  it s propagating non-XML characters   Create some database entries with non-XML characters  NULs  DELs  control characters  et al   and run your XML converter on it  Output the XML to a file and look at it in a hex editor  If this contains non-XML characters  your converter is broken  Fix it or  if you cannot  create a preprocessor that rejects output with such characters   If the converter output looks good  the problem is in your XML consumer  it s inserting non-XML characters somewhere  You will have to break your consumption process into separate steps  examine the output at each step  and narrow down what is introducing the bad characters   Check file encoding  for UTF-16   Update  I just ran into an example of this myself  What was happening is that the producer was encoding the XML as UTF16 and the consumer was expecting UTF8  Since UTF16 uses 0x00 as the high byte for all ASCII characters and UTF8 doesn t  the consumer was seeing every second byte as a NUL  In my case I could change encoding  but suggested all XML payloads start with a BOM

User · Answer

To add to Sonz s answer above  following worked for us     Instead of  XmlString Replace   amp  x0      0x00        use this XmlString Replace   x00     0x00

User · Answer

As kind of a late answer   I ve had this problem with SSRS ReportService2005 asmx when uploading a report       Public Shared Sub CreateReport ByVal strFileNameAndPath As String  ByVal strReportName As String  ByVal strReportingPath As String  Optional ByVal bOverwrite As Boolean   True          Dim rs As SSRS 2005 Administration WithFOA   New SSRS 2005 Administration WithFOA         rs Credentials   ReportingServiceInterface GetMyCredentials strCredentialsURL          rs Timeout   ReportingServiceInterface iTimeout         rs Url   ReportingServiceInterface strReportingServiceURL         rs UnsafeAuthenticatedConnectionSharing   True          Dim btBuffer As Byte     Nothing          Dim rsWarnings As Warning     Nothing         Try             Dim fstrStream As System IO FileStream   System IO File OpenRead strFileNameAndPath              btBuffer   New Byte fstrStream Length - 1                 fstrStream Read btBuffer  0  CInt fstrStream Length               fstrStream Close           Catch ex As System IO IOException             Throw New Exception ex Message          End Try          Try             rsWarnings   rs CreateReport strReportName  strReportingPath  bOverwrite  btBuffer  Nothing               If Not  rsWarnings Is Nothing  Then                 Dim warning As Warning                 For Each warning In rsWarnings                     Log warning Message                  Next warning             Else                 Log  Report   0  created successfully with no warnings   strReportName              End If          Catch ex As System Web Services Protocols SoapException             Log ex Detail InnerXml ToString            Catch ex As Exception             Log  Error at creating report  Invalid server name timeout     vbCrLf   vbCrLf    Error Description      vbCrLf   ex Message              Console ReadKey               System Environment Exit 1          End Try     End Sub   End Function CreateThisReport   The problem occurs when you allocate a byte array that is at least 1 byte larger than the RDL  XML  file   Specifically  I used a C  to vb net converter  that converted    btBuffer   new byte fstrStream Length     into    btBuffer   New Byte fstrStream Length       But because in C  the number denotes the NUMBER OF ELEMENTS in the array  and in VB NET  that number denotes the UPPER BOUND of the array  I had an excess byte  causing this error   So the problem s solution is simply     btBuffer   New Byte fstrStream Length - 1

User · Answer

I m using IronPython here  same as  NET API  and reading the file as UTF-8 in order to properly handle the BOM fixed the problem for me   xmlFile   Path Combine directory str   file xml   doc   XPathDocument XmlTextReader StreamReader xmlFile ToString    Encoding UTF8      It would work as well with the XmlDocument   doc   XmlDocument   doc Load XmlTextReader StreamReader xmlFile ToString    Encoding UTF8

User · Answer

I also get the same error in an ASP NET application when I saved some unicode data  Hindi  in the Web config file and saved it with  Unicode  encoding    It fixed the error for me when I saved the Web config file with  UTF-8  encoding

[.net] Hexadecimal value 0x00 is a invalid character

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