Here's what I did, I have installed svnserve as a service and I started it with the net start svn service command. I typed svn ls svn://localhost to test the service but it returned the error as stated in the title of this post.
I entered svn --version and svnserve --version on my computer to find out the version numbers and the client and the server version is the same, version 1.5.6. I'm guessing the error appears due to different versions of the server and the client.
When I start the server using svnserve --daemon --root command in cmd, The error still appears.
Why does the error appear? Thanks
Make sure you are using the correct svnadmin. For example, if you installed VisualSVN, you will need to use the svnadmin located in the bin folder of the installation directory. I had installed the command line version of SVN...and when I used this version of the svnadmin tool, I got the same error.
I was able to fix this by updating Subversion on the server. I also made the adjustment on the db file. Then I pushed everything backup onto the server as an overwrite. I actually (on windows) did a checkout locally, then the files that were generated in creating that repo, I edited the db, then grabbed all files and pushed them up to SVN on the server.
That seemed to have done the trick.
I installed (the Collabnet install of) SVN 1.5.5 and it was running fine with TortoiseSVN 1.6.1. After upgrading SVN to 1.6.2 I'm getting the same error (Expected fs format between ‘1’ and ‘3’; found format ‘4’) when I try to access it through Trac. This lends credibility to Blair's answer. I'll let you know how I get it running again.
Update: Blair's answer worked for me, too: the message says that an old version of SVN is trying to access the repository, so find it and delete it. The specifics for me were that the error only occurred when I used Trac, so I re-installed Trac on Windows (http://trac.edgewall.org/wiki/TracOnWindows) with the latest installer I could find (svn-python-1.6.1.win32-py2.5.exe) and deleted old eggs from the Python site-packages folder. After a reboot and resync, I was up and running again.
Which Subverson tool did you use to create the repository? TortoiseSVN? Your TortoiseSVN may be newer, a 1.6.x release, then your 1.5 command line client and svnserve, so svnserve 1.5.x cannot serve a 1.6.x repository.
In my fsfs repository created with svnadmin 1.6.1, the db/format file contains