There are WARNINGs when (successfully) installing Opera via Synaptic Package Manager in Ubuntu 13.04
Setting up opera (12.15.1748) ...
Updating software catalog...this may take a moment.
INFO:softwarecenter.db.pkginfo_impl.aptcache:aptcache.open()
WARNING:softwarecenter.db.update:The file: '/usr/share/app-install/desktop/sonic-visualiser:x-sonicvisualiser.desktop' could not be read correctly. The application associated with this file will not be included in the software catalog. Please consider raising a bug report for this issue with the maintainer of that application
WARNING:softwarecenter.db.update:The file: '/usr/share/app-install/desktop/sonic-visualiser:x-sonicvisualiser-layer.desktop' could not be read correctly. The application associated with this file will not be included in the software catalog. Please consider raising a bug report for this issue with the maintainer of that application
WARNING:softwarecenter.db.update:The file: '/usr/share/app-install/desktop/workrave:workrave.desktop' could not be read correctly. The application associated with this file will not be included in the software catalog. Please consider raising a bug report for this issue with the maintainer of that application
Software catalog update was successful.