How to fix Tortoise SVN “Unable to connect to a repository at URL 503 Service Unavailable”

Recently I stumbled across an issue whereby I couldn’t connect to my SVN Repository using the latest version of Tortoise SVN. I trawled the web for solutions based on the error message I received and came up with absolutely nothing that worked. It was frustrating as it was working on my second laptop and I couldn’t figure out why as the settings were identical and I could access the repo via WebSVN.

[ERROR] svn: E175002: Unable to connect to a repository at URL ‘https://mycompaniesserver.com/svn/repo/trunk/project’
[ERROR] svn: E175002: OPTIONS request on ‘/svn/repo/trunk/project’ failed: 503 Service Unavailable

As it turned out the error message is totally missleading. After much trial and error I realised the versions of Tortoise were different. Surely that couldn’t be it, but I downloaded a prior release just to test. I found that the latest version of Tortoise SVN does not work with SVN Server Version 1.7. And interestingly Tortoise SVN 1.8 does not work with SVN Server 1.8 either. Once I downloaded Tortoise 1.7 everything started working again.