A SharePoint migration is one of those projects where the mistakes don't show up until it's expensive to fix them. After 50+ enterprise migrations, these are the twelve I see cost companies the most, and how to avoid each one. For the full process, pair this with my step-by-step migration guide.
Migrations fail quietly
Nobody announces a failed migration. It just drags: content half-moved, two systems running in parallel, users unsure where the real document lives. The failure is the slow bleed of time, trust, and money. Every mistake below feeds that bleed.
1. Skipping the content audit
The first and most expensive mistake. If you don't know what you have, how much, how old, who owns it, you can't plan a migration. An audit tells you what to move, what to archive, and what to delete. Skip it and you pay to migrate junk.
2. Migrating the mess
A migration is a rare chance to clean house. Lifting fifteen years of duplicates, abandoned sites, and stale drafts into your shiny new environment just recreates the old problem in a new place. Clean before you move, not after.
3. Ignoring permissions
Permissions rarely survive a migration intact unless you plan for them. Broken inheritance, missing groups, and over-shared content all carry over, or worse, get scrambled. Given how much permissions matter for security and Copilot, restructuring them is part of the migration, not an afterthought.
4. Losing metadata
Migration tools happily move files while quietly dropping the metadata that made them findable. Document types, statuses, custom columns, gone. Plan your metadata mapping up front, or your team lands in a new environment where search is worse than before.
5. No pilot migration
Migrating everything at once, with no pilot, is how nasty surprises become production incidents. A small pilot batch surfaces the edge cases, permission quirks, oversized files, unsupported content, while they're cheap to fix.
6. Underestimating timelines
Migrations almost always take longer than the tool vendor's estimate, because the tool doesn't account for cleanup, validation, and the human side. Plan realistically and communicate honestly. An eight-month "three-month migration" damages trust as much as budget.
7. Forgetting the users
A technically perfect migration that nobody was prepared for still feels like a disaster to the people living in it. Communication, training, and clear "where things moved" guidance are part of the job. Adoption is the actual goal, not just moved bytes.
8. Trusting tools blindly
Migration tools are powerful but not magic. They miss edge cases: complex permissions, custom solutions, workflows, large libraries, and tenant boundaries. Someone needs to own the cases the tool can't handle, which is exactly where experienced help earns its keep.
9. No rollback plan
If something goes wrong mid-migration and you have no way back, a bad day becomes a catastrophe. Always know how to pause, revert, or run in parallel safely until you've validated the new environment.
10. Skipping validation
Moving content is not the same as verifying it moved correctly. Skipping post-migration validation, checking counts, permissions, metadata, and access, means you discover problems when users do. Validate systematically before you declare victory.
11. Leaving the old system on
Run the old and new systems in parallel indefinitely and people will keep using the old one, splitting your content and defeating the migration. Set a clear cutover date and decommission on schedule, once validation passes.
12. No governance for after
A clean migration with no governance plan degrades right back into chaos within a year. Decide provisioning, permissions, and lifecycle rules for the new environment before you finish, so the mess you just cleaned up doesn't quietly rebuild. My governance framework is a ready template.
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Every mistake here is avoidable with planning. The companies that migrate smoothly aren't luckier, they audited first, cleaned before moving, planned permissions and metadata, piloted, validated, and set up governance for after. Do those things and a migration becomes a fresh start instead of an expensive drag.
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