One way to fix the license file error is to restart the Windows Management Instrumentation service. You can follow the steps below to restart WMI:
• Step 1: Browse to your data path, right-click ClientInfo.xml and change the name of the file to “OldClientInfo.xml.”
• Step 2: Go to the services window, right-click the Windows Management Instrumentation (WMI) service and select Restart.
• Step 3: Right-click Pervasive PSQL Workgroup Engine and then press the Start option.
• Step 4: Close the Services window and then open your Sage 50 accounting software to check if the error is resolved.
If you find that the license file is still showing invalid you can call the Sage customer support number and ask for help.