SVN resolving problem: "containing working copy admin area is missing"

For an instance, we're having this error: "some/folder/.svn containing working copy admin area is missing".

There are lots of solutions here: http://stackoverflow.com/questions/1394076/how-to-fix-containing-working-copy-admin-area-is-missing-in-svn, but here's the one, that worked for me (not the most elegant, I suppose, but it worked):

1. Remove the conflicted folder (if there are some uncommited files, we need to back them up)

cd /your/project/root
sudo rm -rf some/folder
svn up

2. Commit your changes!