How to Migrate SharePoint Online Between Tenants Without Losing Data

Migrating SharePoint Online between Microsoft 365 tenants has become a frequent requirement for companies that merge, restructure, or want to optimize the management of their cloud resources. When done correctly, this process minimizes the risk of data loss, maintains team productivity, and ensures that all documents, permissions, and critical configurations remain intact.

In this comprehensive guide, we will cover:

The fundamentals of SharePoint Online and why it is essential in the migration
Pre-migration preparation: content audit, permission mapping, and dependencies
Choosing the right tools and migration methods
Detailed steps of the migration, from preparation to final validation
Best practices, tips, and critical points to avoid mistakes
Post-migration: verification, training, and continuous support

1. Fundamentals of SharePoint Online and Its Importance

1.1 Why Is SharePoint Online Crucial in Microsoft 365?

Collaboration Hub: SharePoint Online serves as the primary repository for documents, lists, and organizational data. For more details, see the official SharePoint introduction .
Integration with Teams and OneDrive: Many Microsoft Teams features (such as file tabs) and OneDrive for Business (personal libraries) rely on SharePoint as the underlying service. Check out Microsoft’s article on how Teams integrates with SharePoint and OneDrive .
Advanced Permission Management: SharePoint provides a permission model that allows access control from the site level down to individual documents. Find more information in the official SharePoint permissions documentation .

Given its central role, an incomplete or poorly planned migration can lead to the loss of documents, version histories, or configurations that significantly affect daily operations.

1.2 Common Migration Scenarios

Mergers and Acquisitions: Two companies merging their IT resources to operate under a single tenant.
Rebranding or Restructuring: Changes in corporate identity, unification of multiple subsidiaries, or consolidation of scattered environments.
Cost Optimization: Reducing licenses across several tenants to consolidate everything into one, taking full advantage of Microsoft 365 capabilities.

2. Pre-Migration Preparation

2.1 Comprehensive Content Audit

Before starting, it is crucial to have a detailed inventory. Review the SharePoint migration guidance to understand best practices for auditing and planning:

SharePoint Sites (Site Collections): How many sites exist and what type are they (modern, classic, communication, team)?
Subsites and Hierarchical Structure: In classic environments, there could be subsites inheriting permissions.
Lists and Libraries: Check the number of lists and libraries, their importance, and the volume of data each holds.
Document Versioning: Are major and minor versions in use? Do you need to retain the entire version history?
Metadata, Columns, and Content Types: These store key information, such as approval workflows or document classifications.

Audit Checklist

Total size of each site (in GB).
Number of documents per library.
Workflows (Power Automate or legacy) associated with lists.
Retention or eDiscovery configurations.
Integrations with third-party tools.

2.2 Permission and Dependency Mapping

Users and Groups: Identify who has Read, Edit, or Full Control. Check whether there are security or Microsoft 365 groups with external (B2B) members. See details in the external sharing overview .
Workflows / Power Automate: Some workflows depend on service accounts or connections tied to the source tenant. More info in the Power Automate documentation .
Applications and Web Parts: Third-party apps or customizations (SPFx, scripts, etc.) may break if they are not reconfigured in the new tenant.

2.3 Communication and Governance Plan

Responsibilities: Define who will be responsible for the technical side, budget approval, user training, etc.
Timeline: Set dates for the testing phase, the final migration, and post-migration validation.
Governance and Policies: Ensure the new tenant meets organizational security, retention, and compliance requirements (GDPR, ISO, etc.). You can read more in the Microsoft 365 Compliance documentation .

3. Choosing the Right Tools and Migration Methods

To migrate SharePoint Online between tenants without losing data, you have several options. Check out the SharePoint Migration Tool and other third-party solutions:

Microsoft Native Tools
- PowerShell scripts for exporting and importing content.
- Mover.io (formerly Mover), useful for OneDrive migrations but limited for complex SharePoint scenarios. Official Mover site.
- SharePoint Migration Tool (limited, primarily intended for on-premises to cloud migrations). More information .
Third-Party Tools (recommended for more advanced migrations)
- ShareGate: Popular and easy to use, capable of moving complete libraries, permissions, and basic workflows. ShareGate official site.
- AvePoint: Offers robust solutions for large environments and governance features. AvePoint official site.
- Quest On Demand Migration: Specializes in comprehensive Microsoft 365 migrations (Exchange, Teams, SharePoint, OneDrive). Quest official site.
Custom Scripts and Development
- Suitable if you have an IT team experienced in PowerShell and the Microsoft Graph/SharePoint APIs.
- Allows you to automate and customize the migration, though it requires more time and development resources.

Factors to Consider When Choosing a Tool

Data Volume: Total GB and number of documents.
Complexity: Presence of workflows, custom configurations, or highly granular permissions.
Budget: Licensing costs or other solution-related expenses.
Available Timeline: Some third-party tools can speed up the process significantly.

4. Detailed Steps of the Migration Process

4.1 Preparing the Target Environment

Create the New Tenant (if it doesn’t already exist):
Make sure you have the required SharePoint Online licenses and corresponding user accounts. Configure security and compliance directives (data retention, sensitivity labels, etc.). Check the Microsoft 365 security documentation .
Site Structure in the Target Tenant:
Create site collections and communication or team sites that reflect (or improve upon) the organization in the source tenant.
Define templates, initial permissions, and groups, following Microsoft’s recommendations .

4.2 Migrating Users and Permissions

Identity Mapping:
Ensure each user in the source tenant has a corresponding account in the target tenant.
For external (B2B) users, review invitations and shared access.
Roles and Groups:
Replicate SharePoint groups (Owners, Members, Visitors) or take the opportunity to reorganize the permission structure if it’s highly fragmented.
If the organization uses inherited permissions, make sure they remain or are updated in the new environment. See SharePoint site permissions management .

4.3 Migrating Content

4.3.1 Pilot Migration

Perform a test migration with a small site or library to validate the configuration and the tool. Check the migration duration, potential errors, and permission compatibility.

4.3.2 Staged or Bulk Migration

Phase 1: Large libraries (critical departments).
Phase 2: Other libraries and less critical lists.
Phase 3: Workflows, scripts, and apps that require final adjustments.

It is recommended to migrate in stages to reduce risks and allow users to continue working while parts of the content are consolidated.

4.3.3 Versioning and Metadata

Configure the migration tool to preserve version histories, metadata (creation date, modification date, author), and any relevant custom columns. Review SharePoint Online limitations, such as maximum file path length or invalid characters, outlined in the guidance on long file names and paths .

4.4 Post-Migration Validation

Site Structure and Navigation:
Does the site and subsite hierarchy match?
Do internal links correctly point to the new tenant?
Reviewing Lists and Libraries:
Check the number of files and folders to confirm everything was copied over.
Verify that metadata and versions were preserved.
Permissions and Roles:
Ask users from different departments to confirm they have the correct access levels.
Ensure there are no security gaps (e.g., documents that were private but are now open to everyone).
Workflows / Power Automate:
Confirm there are no failures due to changed URLs or credentials.
Update connections if they still point to the source tenant.

5. Best Practices and Tips to Avoid Data Loss

Perform a Backup Before Migration
Even though SharePoint Online is cloud-based, creating an extra backup (or exporting critical libraries) provides security against potential errors. More information on Microsoft 365 backups .
Maintain Constant Communication with Users
Give advance notice of migration dates, maintenance windows, and how to proceed if incidents occur. Consider blocking edits in the source tenant during final migration to avoid “stranded documents.”
Monitor Limits and Performance
SharePoint Online imposes limits, such as the 5,000-item list view threshold and a maximum of 400 characters for file paths.
Schedule Migrations Outside Peak Hours
Carry out critical phases when activity is lower (weekends or nights) to minimize productivity impact.
Review Compliance and Retention
If your organization is subject to regulations (GDPR, HIPAA, ISO), ensure retention and data classification policies are maintained or reconfigured appropriately. Microsoft 365 compliance solutions guide .

6. After the Migration: Verification and Maintenance

6.1 User Acceptance Testing (UAT)

Invite key users (champions) to test the new environment and report any access problems, missing documents, or broken functionalities. Provide a feedback channel to record incidents systematically.

6.2 Training and Documentation

New Links and Processes: If the site structure changed, provide a quick reference guide so each team knows where to find their documents.
Update Manuals and Procedures: Review internal documentation to reflect the new SharePoint Online configuration.

6.3 Ongoing Monitoring and Final Adjustments

Usage Monitoring: Use SharePoint Online usage reports or Power BI to detect drops in activity or access issues. Microsoft 365 activity reports .
Continuous Support: Maintain a support channel (for instance, a Teams space) where users can report migration-related incidents.

7. Common Mistakes and How to Prevent Them

Lack of Planning for Workflows
Failing to update connections in Power Automate or legacy workflows can halt critical processes. Document and adjust each workflow carefully.
Outdated Permissions
Confusion between inherited permissions and new security groups can result in access issues or excessive privileges. Thoroughly map them before migration.
Ignoring Version History
Some tools do not transfer all versions by default. Configure your migration tool to carry over the full version history if needed.
Skipping a Pilot Test
Migrating without a test environment increases the risk of encountering major errors in production.
Overestimating Migration Speed
Moving terabytes of data may take several days, depending on bandwidth, the chosen tool, and Microsoft 365 throttling. Plan realistically.

8. Conclusion

Migrating SharePoint Online between tenants without losing data is a complex process requiring meticulous planning, specialized tools (or carefully designed scripts), and constant communication with users. By following these steps:

Audit the source content and permissions.
Choose the tool or method that best fits your data volume, complexity, and budget.
Conduct pilot tests to detect potential problems early.
Migrate gradually, preserving metadata, versions, and workflows.
Validate the new environment, reviewing permissions, workflows, and critical data.
Train and support your users to ensure a smooth transition.

With proper execution, your organization will retain all information, minimize downtime, and enjoy a unified, secure, and more manageable Microsoft 365 environment.

Need Expert Help with Your SharePoint Online Migration?

If your organization requires professional assistance and you want to ensure a successful migration without risking data loss, Cloudfighters can help. Our team of specialists handles:

Planning the migration (audits, permission mapping, timelines).
Selecting and configuring the best tools.
Carrying out the process from start to finish, with thorough testing and validation.
Providing post-migration support so your team can continue working uninterrupted.

Contact us to find out how we can conduct the entire migration efficiently and securely. At Cloudfighters, your information is in the best hands!