When running a task the following is seen in the Migration Manager for Enterprise Social (MMES) logs:
Performing pre-migration validation.
Cannot verify if user 'user@Domain.com' is an administrator.
Pre-migration validation failed. 'The remote server returned an error: (401) Unauthorized.'
1.) Change the Yammer connection URL to https://www.yammer.com/
To do so: Open the project > under connections chose your Yammer connection > make the needed change.
2.) If step 2 has already been completed and you are getting a (401) Unauthorized error after having already successfully completed MMES tasks in the past, then you may just need to restart the following MMES services in the Windows Services management console and try the starting the task again:
Dell Migration Platform - DMP-Service
SM-Dmp Callback Service - SMDmpCallbackService
