Before reporting this as a bug, I am posting it here as suggested on the “How to report a bug” page.
After upgrading my O/S to Debian 11, and with it the subversion client to version 1.14.1 (r1886195), I started getting the following error whenever I tried to access the server: svn: E175003: The server at 'http://svn/singularis/trunk' does not support the HTTP/DAV protocol I checked to see what the network traffic associated with this and found that there was none. I get the same error attempting make a new checkout. However if I substitute the server’s IP address into the URI it works. It also works with a FQDN. It seems that it failing resolve the hostname. Everything else on the host seems to be able to resolve the hostname. /etc/resolv.conf seems to be correct. It is conceivable that there is a DNS resolver problem. However the error message being produced is completely wrong and grossly misleading. Ian Miller