XML parsing error: XML or text declaration is not at the beginning of the entity

Recently in the modification of Discuz code for customers to use, encountered a problem is that BBS post management in Chrome and Firefox can not load the normal processing, only a layer of processing, and then there is no context.

Debugging discovery is a problem with XML. "XML declaration allowed only at the start of the document ..."

When you encounter an error that is usually an empty line at the beginning of the XML, start looking from the configuration file and delete the header and tail blank lines.

This piece of code is in the _header.html file under template.

</div> <% Else%> <%csharp%> response.clear (); Response.ContentType = "Text/xml"; Response.Expires = 0;      Response.Cache.SetNoStore (); <%/csharp%><br><?xml version= "1.0" encoding= "Utf-8"?> <root> <! [Cdata[<%/if%>

The default is the XML declaration content that is wrapped and written after <%/csharp%>, resulting in an error. Just need it. Declare the line break and the space deletion.