Notice! This page describes the nature of the error using a hypothetical example and not the erroneous data of the input test file. You should however be able to apply this information to your error case.
Error description:
XML declaration is not at the beginning of the file where it should be. XML declaration looks something like this:
<?xml version="1.0" encoding="ISO-8859-15"?>
It should be stated before the actual XML content begins. This error can occur for example if there are multiple XML documents in one file or there is double declaration.
Example:
In this case, extra declaration should be removed.
Error message given by the validator:
"XML declaration allowed only at the start of the document"