This issue has come up a couple of times this week and has also be raised on the OTN JDeveloper Forum, so it seemed to be worth a quick public-service announcement.
Subversion 1.7 introduces changes (AKA complete re-write) into the way that working copies are stored, the implication of this is that a 1.6 client and a 1.7 client cannot operate again the same working copy on a developer's workstation.
Current versions of JDeveloper's SVN support contain 1.6 client code, so if you are mixing and matching JDeveloper and SVN / Tortoise command line operations you will run into trouble.
e.g. The following sequence of operations will fail:
However, the following should work:
Obviously, for convenience and because some operations such as refactoring need to issue SVN commands I'd recommend that, if using a 1.7 repository, you carry out all operations including the initial checkout from within the IDE.
As a general guidance if you are going to upgrade your repository (and my further advice would be not to upgrade at the moment if your primary client is JDeveloper) I'd recommend that you clean up any outstanding transactions before the upgrade, and then, once the server is up to 1.7, do a clean checkout from JDeveloper and stick to working within that environment.