SharePoint Migration to SharePoint Online: Complete 2026 Guide
Planning to migrate from SharePoint On-Premises to SharePoint Online? This comprehensive guide covers the complete migration process, tools, and best practices to ensure a smooth transition.
Why Migrate to SharePoint Online?
- Reduced infrastructure costs: No servers to maintain
- Always up-to-date: Microsoft handles updates and patches
- Better collaboration: Integration with Teams and Microsoft 365
- Mobile access: Work from anywhere on any device
- Enhanced security: Enterprise-grade protection built-in
Pre-Migration Assessment
Before migrating, assess your current SharePoint environment:
1. Content Inventory
- Total data volume (GB/TB)
- Number of site collections
- Number of sites and subsites
- Document libraries and lists count
- Custom solutions and workflows
2. Identify Migration Blockers
- InfoPath forms (not supported in SPO)
- Sandbox solutions
- Classic workflows (consider Power Automate)
- Custom web parts (may need rebuilding)
- Files exceeding 250GB limit
Migration Tools Comparison
| Tool | Best For | Cost |
|---|---|---|
| SharePoint Migration Tool (SPMT) | Small to medium migrations | Free |
| Migration Manager | Large-scale file shares | Free |
| ShareGate | Complex migrations with reporting | Paid |
| AvePoint | Enterprise migrations | Paid |
| Metalogix | Incremental migrations | Paid |
Step-by-Step Migration Process
Phase 1: Planning (2-4 weeks)
- Run SharePoint Migration Assessment Tool
- Create site mapping strategy
- Define URL structure for SharePoint Online
- Plan permission model (SharePoint groups vs M365 groups)
- Create communication plan for users
Phase 2: Preparation (1-2 weeks)
- Clean up content (delete old/duplicate files)
- Fix broken permissions
- Document custom solutions for recreation
- Set up SharePoint Online tenant settings
- Create target site collections
Phase 3: Pilot Migration (1-2 weeks)
- Select a non-critical site for pilot
- Run migration with chosen tool
- Validate content and permissions
- Test with pilot user group
- Document issues and lessons learned
Phase 4: Full Migration (2-8 weeks)
- Migrate in waves based on priority
- Run incremental syncs for active content
- Perform cutover during low-usage hours
- Update DNS/URLs if needed
- Communicate go-live to users
Phase 5: Post-Migration (2-4 weeks)
- Validate all content migrated successfully
- Test critical workflows and integrations
- Train users on SharePoint Online features
- Decommission on-premises servers
- Monitor adoption and address issues
Common Migration Challenges
| Challenge | Solution |
|---|---|
| Large file sizes | Split or archive before migration |
| Complex permissions | Simplify with M365 groups |
| Custom workflows | Rebuild with Power Automate |
| InfoPath forms | Convert to Power Apps |
| Slow migration speed | Use multiple SPMT instances |
SharePoint Online Limits to Know
- File size limit: 250 GB
- File path length: 400 characters
- Items per library: 30 million
- Storage per tenant: 1TB + 10GB per license
- Site collections: 2 million
Expert SharePoint Migration Services
Virtual Petals has migrated 50+ SharePoint environments to SharePoint Online. Our Microsoft-certified consultants ensure zero data loss and minimal downtime.
