[java] Error: The processing instruction target matching "[xX][mM][lL]" is not allowed

This error,

The processing instruction target matching "[xX][mM][lL]" is not allowed

occurs whenever I run an XSLT page that begins as follows:

<?xml version="1.0" encoding="windows-1256"?> 
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:include href="../header.xsl"/>
  <xsl:template match="/">
    <xsl:call-template name="pstyle"/>
    <xsl:call-template name="Validation"/>
    <xsl:variable name="strLang">
      <xsl:value-of select="//lang"/>
    </xsl:variable>
    <!-- ////////////// Page Title ///////////// -->
    <title>
        <xsl:value-of select="//ListStudentFinishedExam.Title"/>
    </title>

Note: I removed any leading spaces before the first line, but the error still occurs!

There was auto generated Copyright message in XML and a blank line before <resources> tag, once I removed it my build was successful.

in my case was a wrong path in a config file: file was not found (path was wrong) and it came out with this exception:

Error configuring from input stream. Initial cause was The processing instruction target matching "[xX][mM][lL]" is not allowed.

Reason for me is 2 of following code in one xml

<?xml version="1.0" encoding="utf-8"?>

I had a similar issue with 50,000 rdf/xml files in 5,000 directories (the Project Gutenberg catalog file). I solved it with riot (in the jena distribution)

the directory is cache/epub/NN/nn.rdf (where NN is a number)

in the directory above the directory where all the files are, i.e. in cache

riot epub/*/*.rdf --output=turtle > allTurtle.ttl

This produces possibly many warnings but the result is in a format which can be loaded into jena (using the fuseki web interface).

surprisingly simple (at least in this case).

Another reason of the above error is corrupted jar file. I got the same error but for Junit when running unit tests. Removing jar and downloading it again fixed the issue.

Xerces-based tools will emit the following error

The processing instruction target matching "[xX][mM][lL]" is not allowed.

when an XML declaration is encountered anywhere other than at the top of an XML file.

This is a valid diagnostic message; other XML parsers should issue a similar error message in this situation.

To correct the problem, check the following possibilities:

1. Some blank space or other visible content exists before the <?xml ?> declaration.

   Resolution: remove blank space or any other visible content before the XML declaration.

2. Some invisible content exists before the <?xml ?> declaration. Most commonly this is a Byte Order Mark (BOM).

   Resolution: Remove the BOM using techniques such as those suggested by the W3C page on the BOM in HTML.

3. A stray <?xml ?> declaration exists within the XML content. This can happen when XML files are combined programmatically or via cut-and-paste. There can only be one <?xml ?> declaration in an XML file, and it can only be at the top.

   Resolution: Search for <?xml in a case-insensitive manner, and remove all but the top XML declaration from the file.

For PHP, put this line of code before you start printing your XML:

while(ob_get_level()) ob_end_clean();