I recently upgraded my Subversion server to VisualSVN Server 2.1 and started experiencing this issue again:
svnsync: OPTIONS of 'https://xxx/svn/TentacleSoftware': Server certificate verification failed: certificate issued for a different hostname, issuer is not trusted (https://xxxx)
It looks like the account under which the VisualSVN Server service runs has been changed, breaking my account profile work-around.
Some digging in Google revealed a more elegant solution to the problem; specifically set the configuration cache directory in the command line to a static location, so that any saved/accepted certificates are persisted between accounts.
As my normal user account on the server, I ran the following command:
svnsync sync https://xxx/svn/TentacleSoftware --config-dir "D:\Repositories\Config"
That let me permanently accept the certificate and saved the configuration to the specified directory. After appending the same config-dir option to my post-commit hooks, the service was able to sync as normal:
svnsync --non-interactive --trust-server-cert sync https://xxx/svn/TentacleSoftware --config-dir "D:\Repositories\Config" --source-username xxx --source-password xxx --sync-username xxx --sync-password xxx
Much nicer than my previous solution.