Problem

During migration of Google Groups to an Office 365 shared mailbox, you have noticed following error:
“Fatal Error in Group Migration of [Name of Group] Error during folders binding: The specified folder could not be found in the store.

Cause

During a migration, the platform will check whether the target shared mailbox exists.
If it doesn’t exist yet in your target Office 365, the platform will create it.
Sometimes there is a delay of creating a shared mailbox on the Microsoft side. So the platform tries to push your mails to the not yet existing object you hit the indicated error.

Resolution

Normally, there is a timeout after a creation a shared mailbox to avoid such cases.
If you have this error anyway, try to restart your migration later.