Failed to migrate Planner comments.
The error will appear as the following in the task events. It can either be "Unexpected error occured" or" Error Message: Exception of type 'Quest.OnDemand.Migration.Teams.Exceptions.ActivityTransientException' was thrown". When you are seeing such errors, make sure you check the events which were generated at that time previously, you will most likely find an indication of what failed / caused the issue.
The Planner task comments are emails that are sent to the Group mailbox by the migration service account.
If there are any mail flow rules around the path, the comments will not be posted.
Ensure there are no mail flow Rules in the Exchange Admin Center that would block the flow for the migration service account sending emails to the group mailbox.
Exchange Admin Center --> Mail flow --> Rules
Disable all the rules related to migration service account or groups which are being migrated.
