In order to solve some of the nepomuk/akonadi problems you must follow ALL these steps:
1. Stop nepomuk and strigi in systemsettings (advanced tab)
2. You must delete all the nepomuk related stuff:
rm -Rv ~/.kdemod4/share/apps/nepomuk
rm -v ~/.kdemod4/share/config/nepomuk*
3. Now you must REBOOT
4.Finally check again systemsettings in order to start again nepomuk/strigi (maybe this step is not necessary)
5.You can also check the akonadi server ( alt+f2 -> akonaditray ) maybe you must restart the server.
This solve some problems if this not work you can try at a last resource to follow the post "How-to update kdemod 4.3.4 to 4.4.0" to completelly delete and reinstall kdemod packages.
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