svn: Cannot write to the prototype revision file of transaction '7391-1' because a previous representation is currently being written by this process
- Locate the offending transation (not the one in the error!):
svnadmin lstxns /path/to/repository
Repeat this step several times over a few minutes to ensure that it is actually stuck and not just slow.
- Remove the offending transaction (change the id based on the first step):
svnadmin rmtxns /path/to/repository 6265-1