Comment 2 for bug 555228

Thanks for reporting this issue, Fernando!

Strangely, this is a duplicate of a bug whose fix has been recently released, however your report shows the version number containing the fix (0.75.9) along with a stack trace showing an older version of the code. Can you please make sure that your system is up to date, and possibly reinstall the software-properties-kde package to make sure the installation is not broken? (use 'sudo apt-get update && sudo apt-get install --reinstall software-properties-kde' in the terminal). After this, please report back whether you still get the same error or it is fixed. Thanks!