You may encounter this issue if your Respondus project folder was stored in your My Documents or Desktop. The Migration to OneDrive changed your Documents path.

To Resolve this issue.

1. Open Respondus 4.0 and dismiss the error message.
2. Click File and the Preferences.
   
   
3. In the preferences window click update next to Folder.
   
4. browse to the location of your Respondus project folder then select ok. The new location should be c:\users\"username"\OneDrive - Des Moines University\Documents\Respondus Projects.
   
5. Close and reopen Respondus 4.0. It should now open without any errors.

Optional: Set Respondus Projects folder to always be available

1. Browse to Respondus Projects folder in File Explorer. 
2. Right click on the Respondus Projects folder and select aways keep on this device.
3. The folder will get a solid green circle with a white checkmark.