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Migration

What should I check before a Microsoft 365 migration?

By Suresh Girinathuni

Quick answer

Assess the source environment (volume, item counts, versions, workflows), map permissions, sharing links, and external guests, find long paths and blocked file types, confirm owners for every source, design the target hubs, sites, libraries, and metadata first, clarify security and retention requirements, choose tooling and prove it with a pilot wave, then set communication dates and define what “validated” means before production migration begins.

Key takeaways

  • Inventory, permissions, restrictions, and ownership come before tooling.
  • Design target IA first; never migrate into an undesigned tenant.
  • Prove readiness with a pilot; define “validated” up front.

Detailed Explanation

Assess the source environment (volume, item counts, versions, workflows), map permissions, sharing links, and external guests, find long paths and blocked file types, confirm owners for every source, design the target hubs, sites, libraries, and metadata first, clarify security and retention requirements, choose tooling and prove it with a pilot wave, then set communication dates and define what “validated” means before production migration begins.

How it works

Treat pre-migration as its own phase: inventory with tooling reports, triage content into migrate/archive/delete, map the target IA, remediate blockers, pilot one or two libraries end to end, and only then schedule bulk waves with exit criteria per wave.

Limitations and considerations

Skipped cleanup migrates sprawl into the new tenant at full cost. Identity, licensing, and admin consent for the migration tool must be ready before the first byte — they are the most common day-one blockers.

This Q&A page is the short-answer layer for “What should I check before a Microsoft 365 migration?” Use the related guides below when you need implementation steps, architecture trade-offs, or troubleshooting detail.

For broader context, visit the Migration Hub. It connects this topic to surrounding Microsoft 365, Power Platform, SharePoint, Copilot Studio, Dataverse, migration, and Dynamics 365 guidance.

When to use it

Run this checklist at program start and re-verify before each wave; migration readiness decays as sources keep changing.

Practical example

A Dropbox program inventories 40,000 files, archives 30% stale content, fixes 22 long paths, pilots two libraries, then commits to dated bulk waves with owner sign-off gates.

Related Questions

What is Microsoft 365 migration?Microsoft 365 migration moves users, documents, collaboration workloads, and related configuration into Microsoft 365 services.How long does a SharePoint migration take?There is no universal duration: a small library moves in days while enterprise programs run weeks to months. Data volume, item count, versions, permissions, remediation, throttling, and validation depth set the timeline — not copy speed alone.What should be validated after a SharePoint migration?Validate counts, failures, metadata, versions, permissions, sharing, folder structures, links, and business-critical functionality.What is tenant-to-tenant migration?Tenant-to-tenant migration moves mailboxes, SharePoint, Teams, OneDrive, and identity configuration from one Microsoft 365 tenant to another — typically after mergers, acquisitions, or divestitures — with coexistence and cutover planning.

Related nextM365 Guides

MigrationMicrosoft 365 Migration Checklist for BeginnersA practical Microsoft 365 migration checklist for beginners, covering scope, inventory, cleanup, licensing, identity, permissions, pilot migration, migration waves, validation, communication, and post-migration support.MigrationSharePoint Migration AssessmentAssess your content, permissions, metadata, customizations, workflows and dependencies before planning a SharePoint migration.

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