svn: E125012: Invalid character in hex checksum

I was recently running Fedora 22 x64 with svn version
subversion-1.8.13-7.fc22.x86_64 (possibly but unlikely as low as
subversion-1.8.13-2.fc22.x86_64). svn was functioning just fine in all
regards. Everything was installed all on a single server, code, svn
service, the lot.
My format is version 3.

I then did an upgrade to Fedora 23 which installed
subversion-1.9.3-1.fc23.x86_64

Now, commands like svn checkout, svn commit, svn list (anything that
needs to talk to the svn service) all return "svn: E125012: Invalid
character in hex checksum" immediately.

I have rolled the /var/svn files (the subversion database) back to
multiple versions in the past but all with exactly the same outcome.
This problem does not appear to be corruption in my database. It appears
to be something that changed in the upgrade from 1.8.13 to 1.9.3.

I can install a Fedora 22 VM with the old svn version and try and access
the database, but that will still not allow me to access it from the
newer svn version.

Is there something I need to do to upgrade the database between these
versions?
Received on 2016-01-22 00:10:10 CET