When you try to log in on DMP and you get the error shown on picture 1,
You can follow use the following instructions to fix this issue.
1. Go to S4M_DM file location in this example it will be the following: C:\S4M_DM (Picture 2)
2. Browse to S4M_DM/DMETL(C:\S4M_DM\DMETL) and look for the file named: ServiceStack.Text.dll (Picture 3)
4. Copy this .dll file and paste it in the following file: C:\S4M_DM\DMP\Bin (Picture 4)
5. After you've placed the .dll file you must restart the services.
6. When the services have been restarted the DMP screen will appear and you can log in.