Unfortunately, from time to time, I have to use SharePoint Designer. However after renaming my account I started getting this error:
Server error: The version of Microsoft SharePoint Foundation running on the server is more recent than the version of SharePoint Designer that you are using. You need a more recent version of SharePoint Designer
While this error can be caused by the actual error message, in my case it was completely bogus.
SPD was trying to login with a cached credential. The account wasn't valid any more.
Clearing the 2 SharePoint Designer cache locations didn't work.
Un-installing and re-installing SPD didn't work.
The credential was cached in windows credential manager. However if you look there, you probably won't notice the trees for the forest. In my case I just cleared the lot using a handy batch file from https://gist.github.com/tomfanning/77f20a1bb50055e915f4.
The downside of running that is that it will remove all your cached credentials.