Can not create new categories or install package

Hi all

Since today, I’m no longer able to install new packages or create a category somewhere in the tree.

When I click on "New Category", the window pops up, I can enter the desired name but when I click on save, the progress bar raises to about 60%, then I get the following error: While trying to create the category, there was an error (might by slightly different message, I’m translating from german to english).

The same happens while installing new packages.

I’m a little lost. As far as I can tell, nothing was changed on the system.

Thank you