edit-Link on Category page doesn't work

[+PISA-caching]

When I open the "My Categories" page, every category that I may edit has an [edit] link, that works just fine.

 

But when I open one of these categories, I also find an [edit]-link, but this one always responses with "An Error Has Occurred". This makes it difficult to edit a category, that is not yet official, as these categories don't show on the "My Categories" page. The only workaround I found so far is to copy one edit-link on the "My Categories" page and replace the guid-parameter with the ID of the category that I really want to edit.

[+elyob]

I can confirm the same error response.

[+PISA-caching]

Update: The link "Edit Category" on the right works all the time.