When the web_service_access_only field in the sys_user table is set to true for a user with the mid_server role, MID Server validation fails, and the following error is displayed:

User mid_user is not allowed to access the given processor: no thrown error 

This issue is related to the error in KB0598956, in which the mid_server role configuration caused validation to fail.

1. Navigate to User Administration >  Users.
2. Open a record for a user that has the mid_server role.
3. Select the Web service access only option.
4. Save the record.
5. Create a new MID Server.
6. Try to validate the new MID Server. 
   Note the log message: User mid_user is not allowed to access the given processor: no thrown error

1. Clear the Web service access only option in the sys_user record.
2. Re-validate the MID Server.