First, please bear with my ignorance here. I only just figured out that I don't get a reply to my e-mail in my inbox. I'm apparently supposed to visit this page...
Anyway, thank you for replying. To return to the problem: >Does the problem occur with an upgraded working copy or with >a new checkout? The answer is: with both. >Can you please try a new checkout if you haven't already? When it first happened (after upgrading) I tried a new checkout. But only for one of the directories. Right now I checked out the two directories I'm currently using. And I still get the same error message if I simply click SVN update. Only if I commit (just anything) first and then update, it works fine - and only for that directory it works.