[SOLVED] After upgrade, no finish task for new,edit, remove sites or apps.

In the server table, change the value of the field 'dbversion' to 86, then do an ispconfig update with ispconfig_update.sh command again and choose 'git-stable' as target. Then test if it works now. At least the last database update could not be installed and this causes the issues on your system as the database layout is not compatible with the program code at the moment.