Seen errors like this, e.g. upon "svn update" issued on a remote machine when the repository is on a server:
svn: Berkeley DB error for filesystem '.../Repositories/proj/db' while opening 'nodes' table: Invalid argument svn: bdb: file nodes (meta pgno = 0) has LSN . svn: bdb: end of log is  svn: bdb: .../Repositories/proj/db/nodes: unexpected file type or format
Not sure what the main cause is, but it could be a bug with svnserve since it is the one who is running as root. Login with ssh on the server and cd to the directory mentioned in the error:
cd Repositories/proj/db ls -l [...] -rw-r--r-- 1 root goblin 1048576 Aug 4 17:42 log.0000000095 -rw-r--r-- 1 root goblin 1048576 Aug 4 17:52 log.0000000096
Notice that there are files whose owner is root while the other files (not shown) are owned by globlin. We can fix that with chmod:
sudo chown goblin log.000000009* cd ../.. svnadmin recover proj
Back on the remote machine, try again to run "svn update".