I saw this error in the OS Application Event log "TimeStr is invalid"
What does this mean?
You do not have permissions to the OS 'Temp' directory on the Migration Control Center (MCC) and/or migration workstations.
Make sure your account is not restricted by any GPO's,
Confirm 'User Account Control' (UAC) is disabled.
Open Windows File Explorer, to the 'Windows\Temp' directory.
You will receive an error stating you do not have access to this folder.
Click, 'Yes' to grant access to the 'Temp' folder.
Retry your migrations