[KevinH]

Yes, definite bug in Sigil code here. It looks like a really old one as well.

This regular expression to fix xml declarations in ImportEPUB.cpp is not properly restricted and it is causing the problem:

.//Misc/HTMLEncodingResolver.cpp:const QString VERSION_ATTRIBUTE    = "version\\s*=\\s*(?:\"|')([^\"']+)(?:\"|')";

.//BookManipulation/XhtmlDoc.cpp:const int XML_DECLARATION_SEARCH_PREFIX_SIZE = 150;


QString ImportEPUB::PrepareOPFForReading(const QString &source)
{
    QString source_copy(source);
    QString prefix = source_copy.left(XML_DECLARATION_SEARCH_PREFIX_SIZE);
    QRegularExpression version(VERSION_ATTRIBUTE);
    QRegularExpressionMatch mo = version.match(prefix);
    // MASSIVE hack for XML 1.1 "support";                                                                                      
    // this is only for people who specify                                                                                      
    // XML 1.1 when they actually only use XML 1.0                                                                              
    source_copy.replace(mo.capturedStart(), mo.capturedLength(), "version=\"1.0\"");
    return source_copy;
}

This bug will hit any content.opf file that does not start with a proper xml declaration. This bug has been in Sigil for a long time. The package version tag did not matter much in earlier versions of Sigil but it does now since we need it to properly detect epub 3 from epub 2.

I will look into fixing this by restricting it to the xml declaration.

Thanks for the bug report!

KevinH