Dear Ulrike,
Hm. yes. I can change it in catchfile and use your fix instead. But why are the quotes a problem? \@filelist can currently contains file names with quotes also in other cases -- not really probable but possible.
It would be best if we were able to support quotes in \@filelist file names. I just didn't find how. This is just one of TeX4ht internals that I still don't really understand what is going on. I even couldn't find the place where the error actually happens.
Best regards, Michal
