You could edit the module to display which tag was mismatched. The error probably occurred at the last occurrence of that tag before the given line. You could maybe add some meta data to provide an even clearer message.

Update: Well, it appears it's not simple to update the message as it originates in expat, an external library. But that means you'll get a different message if you use a different backend for XML::Simple. For example, if you change 

$XML::Simple::PREFERRED_PARSER = 'XML::Parser';

[download]
to 
$XML::Simple::PREFERRED_PARSER = 'XML::LibXML::SAX';

[download]
You get 
Entity: line 12: parser error : Opening and ending tag mismatch: ERROR line 8 and ROOT
</ROOT>
       ^
Entity: line 13: parser error : Premature end of data in tag ERROR line 8

^
Entity: line 13: parser error : Premature end of data in tag ROOT line 3

^

My test shows that XML::Parser is the fastest backend for XML::Simple, but you can switch to a slower parser that gives better error messages for debugging.

In reply to Re: XML::Simple giving a non-specific error by ikegami
in thread XML::Simple giving a non-specific error by liverpole

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