It looks like some info is broken. Which seems to happen during merge with tree conflicts.
I had to fix the svn database which is the file .svn/wc.db.
WARNING! You are manipulating the svn database which can be harmful! Do this only if you have a backup and if this procedure does not help, restore the data from backup.
- Go to SQLite from SQLite Download Page, download the archive of the precompiled binary for your platform and extract it e.g. to /tools
Change into the .svn directory make a backup of the wv.db (!) and run sqlite3 with wc.db as parameter. E.g.
\tools\sqlite3.exe wc.db
Search the entries causing the problem with
select * from actual_node where conflict_data like '%missing%';
or
select * from actual_node where conflict_data like '%obstructed%';
refine these queries until only the faulty actual nodes are listed. Also
select * from actual_node where local_relpath like '%...%';
is helpful to find the faulty nodes.
Remove the faulty nodes by replacing the select with a delete
delete from actual_node where conflict_data like '%missing%';
Check again with your favorite svn tool.
- Rinse and repeat until all problems are gone.
WARNING! You are manipulating the svn database which can be harmful! Do this only if you have a backup and if this procedure does not help, restore the data from backup.
For me it worked several times.