Error: The specified URI is not a valid server-based translation memory URI. Parametername: uri Trados blocked!

 When trying to select Translate single document I get the following message: The specified URI is not a valid server-based memory URI. Parameter name: uri.
Then when I click OK I get the window to select languages but as soon as I try to select the first language I get the same message. I cannot use Trados and cannot work.
Software patches and updates are installed. This problem has been known and discussed for a while now but apparently not solved. Any new solution?

Thank you for your help

Best

Catherine