How a lean team at Avanade delivered a 2,000-site migration with ShareGate

A French manufacturing company was running a hybrid SharePoint environment. Newer workloads had already moved to SharePoint Online—mostly driven by Microsoft Teams adoption—but the company's legacy content was still sitting on SharePoint 2010 servers on-prem.  

It's a situation that's about to get a lot more common with SharePoint 2016 and 2019 reaching end of support in July 2026, and 70% of organizations that we surveyed saying they still had at least some data on those servers in March 2025.

Avanade’s client wanted to consolidate everything in the cloud and decommission their servers, eliminating ongoing infrastructure costs in the process.  

Straightforward goal. Not a straightforward environment.

2,000 sites, 2 people, and a decade of accumulated complexity

The scope was big: 2,000 SharePoint sites and more than 1.3 TB of data. And because the source was SharePoint 2010, the environment carried over a decade of accumulated complexity, like InfoPath forms, sandbox solutions, custom workflows, and JavaScript injections buried deep in site pages.

Avanade assigned a team of two to handle the migration: Aimery Thomas, Microsoft MVP and Modern Workplace Manager at Avanade was the technical lead and there was one junior developer helping out. An architect checked in a couple of times a week, but the day-to-day execution sat squarely on their shoulders.

For a project of this scale, the team needed tooling that could handle the heavy lifting. There was no room for manual processes or duct-taped workarounds.

Hidden risks that standard tools couldn't catch

Beyond the obvious challenges, Aimery worried about what he couldn't easily see. Script injections—JavaScript embedded directly in SharePoint pages—are notoriously hard to detect. Microsoft's SharePoint Migration Assessment Tool couldn't identify them.

"We had to build an on-prem PowerShell script to identify those kinds of hidden complexities," said Aimery.

If those hidden complexities weren't caught before migration, they'd surface as errors after. At which point, they'd be much harder and more expensive to fix.

Assessment first: cutting the project in half before migrating a single site

Aimery's first move wasn't migrating. It was understanding exactly what they were dealing with.

Using ShareGate Migrate source analysis report, the team assessed all 2,000 sites in their SharePoint 2010 environment. The first discovery was a big one: roughly 1,000 sites had seen zero activity for more than two years.  

With the company’s agreement, those inactive sites were taken out of scope, cutting the project by 50%. That meant a significantly smaller project timeline and lower migration costs before a single site had been moved.

"Make sure to spend enough time on the assessment of the source. Because you just might be able to take half of the sites out of scope," said Aimery.

The team then ran a deeper analysis on the remaining 1,000 sites, classifying each one against a set of complexity criteria: InfoPath forms, running workflows, sandbox solutions, and script injections. Sites that had any of those criteria were flagged as complex.  

The result: about 800 simple sites and 200 complex ones. Simple sites would go first. Complex sites would be given more time.

That triage turned a sprawling, overwhelming project into two manageable phases with a clear plan of attack.

Automated execution with full visibility

With the scope defined, the team migrated the 800 simple sites in four waves. Each wave was balanced by a mix of site sizes and file counts to keep execution predictable.

Aimery, with his developer background, leaned heavily on ShareGate's PowerShell module. The team scripted the entire process: creating target SharePoint Online sites and triggering migrations programmatically, all without needing to work through the graphical interface.

"What I found most useful is being able to run my ShareGate migrations with PowerShell,” said Aimery. “During the migration process we had so many other things to do. But for the migration, we just had to trigger the execution of a script and everything was done automatically."

But automation didn't mean flying blind. Even with everything running via PowerShell, the team could track real-time migration progress through ShareGate's UI, giving them developer-grade control with visual oversight. For a consulting team delivering migrations as a service, that combination is what lets a two-person team run a project that might otherwise need four or five people.

Trusting the reports

After each wave, the team relied on ShareGate's migration reports to confirm that permissions, documents, metadata, and everything else had landed where they were supposed to.

"We really relied on the ShareGate migration reports,” Aimery explained. “If the report said everything was successful, we trusted it."

The wave approach also built in natural safety nets. While the team migrated wave two, end users from wave one had weeks to check their sites. Aimery's team was available for hypercare throughout, but no missing documents were reported.

When reports did flag issues, the team had a system for that too. They maintained a mapping file that linked each error type from the ShareGate reports to a specific corrective action. For example, lookup column issues were resolved by running an incremental migration. No guesswork, just a documented playbook.  

It's the kind of process that scales. The same mapping file and error-handling approach can be picked up and reused on the next client engagement without starting from scratch.

Complex sites: less complex than expected

For the 200 complex sites, the team migrated the content first, then assessed what actually needed rebuilding. Aimery discussed each site's workflows with the client. In most cases, they confirmed they no longer needed them.

Out of all the complex sites, only seven workflows required rebuilding in Power Automate. A final incremental migration caught any content changes made during the rebuild period, and the project was done.