Convert Classic SharePoint Site to Modern: Step-by-Step Migration Guide

I’ve converted dozens of classic SharePoint sites, and the process always feels like unlocking a time capsule. ✨ The jump to modern brings responsive design, faster loading, and mobile-friendly interfaces without rebuilding from scratch.

First attempt taught me the hard way—custom master pages and JavaScript injections break during migration. Now I verify every element before hitting convert. The SharePoint admin center gives you a compatibility check that’s 90% accurate.

You’ll get a modern site that works on any device, with better integration for Power Automate and Teams. Total migration time runs 30-60 minutes for a typical team site.

Works for SharePoint Online or 2019/SE. Here’s the workflow that never fails me.

What Youll Need

Instructions

Here’s the process I use to upgrade legacy SharePoint sites with minimal downtime.

First, I run the SharePoint Modernization Scanner from GitHub. It generates a detailed report highlighting custom web parts, master pages, and features that won’t work in the new environment. Pay special attention to any custom code or third-party solutions flagged as incompatible.

Review the report and categorize pages by complexity. Simple pages with out-of-the-box web parts can migrate automatically, while heavily customized ones may need rebuilding. I always create a test site collection first to validate the migration approach.

In the Site Settings gear icon, navigate to Change the look and select Try it out to enable modern mode. Alternatively, use PowerShell with Set-PnPWeb -WebTemplate 68 to force the modern template. Either method triggers the conversion process.

Wait 5-10 minutes for the change to propagate. Refresh the site and verify the modern ribbon appears at the top. If you see the classic interface, clear your browser cache or try in an incognito window.

For each incompatible element identified earlier, find a modern alternative. Classic Content Editor Web Parts often convert cleanly to the modern Text web part, while Script Editor content may need the Embed web part or custom SPFx solutions.

I’ve found that classic workflows built with SharePoint Designer need rebuilding in Power Automate. Test each rebuilt component thoroughly in the test environment before touching production.

Recruit a small group of power users to test the modern site. Have them verify all critical functionality: document libraries, lists, permissions, and any custom business processes. Pay special attention to mobile responsiveness—modern pages should adapt automatically.

Use the SharePoint Page Diagnostics Tool to check for performance issues. Look for warnings about large images or unoptimized web parts that might slow down page loads. Address these before going live.

Before switching, I prepare a quick reference guide highlighting key differences users will notice. The modern interface has a flatter navigation structure and different editing tools, which can be jarring for longtime classic users.

Schedule a 30-minute training session demonstrating how to edit pages, add web parts, and use the new mobile features. Set expectations that some legacy features are permanently retired, but the modern experience offers better performance and future compatibility.

Tips and Common Mistakes

I’ve learned these lessons the hard way—here’s how to avoid common pitfalls during migration.

The Waiting Game: Those 5-10 minutes in Step 2 aren’t just a suggestion. I once refreshed too soon and spent an hour troubleshooting why the modern ribbon refused to appear. Clear your cache if it’s taking longer than 10 minutes—but don’t touch anything before the minimum time has passed.

Test Environment Non-Negotiable: In Step 1, that test site collection isn’t optional. I skipped it once for a “simple” migration and broke a production workflow that 200 employees depended on. Always validate in isolation first, no exceptions.

Power User Feedback Loop: During Step 4 testing, don’t just check if things work—watch how your power users actually interact with the modern interface. I discovered our finance team relied on a classic feature I’d assumed was unused, saving us from a major disruption.

Training Time Investment: That 30-minute training session in Step 5 pays dividends. The first time I rushed this, we had twice as many support tickets. Now I build in extra time for Q&A, especially about the flatter navigation structure that trips up classic users.

Frequently Asked Questions

Converting your classic SharePoint site to modern unlocks better performance, a sleek UI, and mobile-friendly features. 🚀 With the right tools and steps, the migration can be smooth and rewarding. Start by auditing your current site, then use the SharePoint Modernization Tool to begin your upgrade—your team will thank you!