.svn/tmp directory may be missing or corrupt
10-25-10
I recently spent a substantial amount of time trying to fix an error I got after installing a new subversion client. “your .svn/tmp directory may be missing or corrupt”. The message indicates to run a cleanup, but cleanup just gives the same error.
After some Googling I found a Linux command that will fix the problem, but no Windows version. Here’s a functionally equivalent command that will fix it in Windows:
for /R /D %i in (.svn) do if exist "%i" mkdir "%i/tmp"
You will need to open a shell, cd to your code directory, then run the above command. It will place a new tmp directory inside each .svn directory.
After you run the command, your svn cleanup should succeed and you’ll be able to continue working as usual.

This worked for me, too. Thanks a lot for posting your solution here – it saved me a lot of effort.
Oh my goodness, thank you so much for posting this. I cleaned my hard drive of empty folders without even a thought about possibly corrupting my svn repo. I did not realize how many friggin’ empty tmp folders it uses. Saved me hours of trying to figure out to use a dos command to recursively search for missing tmp folders and create them.
You are a lifesaver!