this is likely not a bug. try running this command
yelp /usr/share/gnome/help/files-and-docs/C/files-and-docs.xml
and see if you get the same error message
yelp /usr/share/gnome/help/about-ubuntu/C/about*
should open the about Ubuntu help. if these files are corrupted you will probably need to reinstall the package ubuntu-docs
this is likely not a bug. try running this command gnome/help/ files-and- docs/C/ files-and- docs.xml
yelp /usr/share/
and see if you get the same error message
yelp /usr/share/ gnome/help/ about-ubuntu/ C/about*
should open the about Ubuntu help. if these files are corrupted you will probably need to reinstall the package ubuntu-docs
sudo apt-get install ubuntu-docs