Resolving storage & licensing check failures

The pre-flight check panel on the Review step compares source data sizes against destination quotas before any data moves. There are three workload-specific checks: mailbox quota (Email), tenant storage quota (SharePoint), and per-user drive quota (OneDrive). Teams migrations have no storage check.

• Email: each source mailbox size is compared to the destination Exchange Online quota (50 GB for Plan 1, 100 GB for Plan 2).
• SharePoint: total source site data is compared to destination available storage (tenant quota minus currently used).
• OneDrive: each source user's drive is compared to their destination per-user quota (default 1 TB for Business plans).

Mailboxes flagged amber need Exchange Online Plan 2. Mailboxes flagged red exceed the 100 GB Plan 2 primary mailbox limit and require an online archive. Resolve before launching.

• In Microsoft 365 admin center → Users → Active users, find the affected destination user.
• Edit their licences and add Exchange Online Plan 2 (or Microsoft 365 Business Premium / E3 / E5, which includes Plan 2).
• For mailboxes over 100 GB: enable the Online Archive in Exchange Admin Center → Recipients → Mailboxes → Mailbox features → Archive mailbox → Enable.
• Items that exceed the 100 GB primary quota will be placed in the archive automatically during migration.

If the selected mailbox count exceeds the number of licensed destination mailboxes, some users will not have an Exchange Online mailbox to migrate into.

• In Microsoft 365 admin center → Billing → Licences, check available Exchange Online licence count.
• Purchase additional licences if needed and assign them to the destination users before launching.
• Alternatively, reduce the migration scope by skipping mailboxes you do not need to migrate.

If total source data exceeds destination available SharePoint storage, the migration will fail part-way through. You must either add storage or reduce scope.

• Option 1 — Add storage: in Microsoft 365 admin center → Settings → Org settings → SharePoint, increase the storage limit. Storage is purchased in 1 TB increments.
• Option 2 — Reduce scope: in the site mapping step, mark large archive sites as 'Skip'. These can be migrated in a separate job once more storage is purchased.
• Option 3 — Clean up destination: delete unused sites or move large files to archive in the destination tenant to free space before migrating.
• After making changes, return to the wizard Review step — the check re-runs each time you load the step.

An amber warning appears when the migration would consume more than 90% of remaining destination storage. This is not a blocker but is worth addressing — leaving less than 10% free risks future quota issues.

• Purchase an additional 1–2 TB of SharePoint storage as a buffer.
• Or skip any very large sites that are not business-critical and migrate them later.

Sites over 1 TB are flagged as slow-migration candidates. They will still migrate, but at much slower speeds due to Graph API throttling. Running them in a dedicated job avoids blocking other sites.

• In the site mapping step, skip the large site from the current job.
• After the current job completes, create a new SharePoint migration job that contains only the large site.
• Schedule the large-site job to run overnight when there is less Graph API competition.

Users whose source drives exceed the destination quota will not fully migrate. You must increase their destination quota before launching.

• In SharePoint Admin Center → Users, find the affected destination user.
• Click their name → OneDrive settings → Storage quota. Change from the tenant default to a custom value in GB.
• Microsoft 365 Business and Enterprise plans support up to 5 TB per user via self-service. Above 5 TB requires a support request to Microsoft.
• For drives approaching 5 TB, contact your Microsoft account team proactively — provisioning large quotas can take 24–48 hours.

After making quota and licence changes in the Microsoft admin center, return to the TheMigrator wizard Review step. The checks re-run automatically each time the step loads — wait a few minutes for Microsoft's changes to propagate before re-checking.

• All panels should show green (pass) before clicking Launch migration.
• Amber warnings will not block the launch, but document them and have a plan to address the remaining space.
• If a panel still shows red after fixing the issue, check that Microsoft's changes have propagated — it can take up to 15 minutes.