Hit by "401 Unauthorized" during PST imports? This showstopper often stems from expired credentials or missing permissions. Renew expired SAS tokens, assign the Mailbox Import Export role in Exchange Online, and configure MFA exclusions.https://joripress.com/how-to-fix-unauthorised-error-401-when-importing-pst-to-office-365

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This critical Office 365 roadblock halts migrations cold, usually due to expired credentials, missing roles, or MFA conflicts.