database not online after upgrade

hallo, i'm new to RDM and took over the issue after a colleague left the company.

i had to upgrade the devolution server to v4.5 (including .net framework to 4.6.2) and the client to 12.5 .

from the server console i can test the database and server connection and i get a "successfull" back.

but i'm not able to connect via local client or via webpage...

on the server (windows server 2008 R2) i get the attached message when i try to open the RDM.

can someone help here?

thanks in advance...

Dom