Migrating from Team Foundation Server (TFS) to Azure DevOps (previously known as Visual Studio Team Services or VSTS) involves moving your source code, work items, build and release pipelines, and other related assets from TFS to Azure DevOps. Here’s a high-level overview of the migration process:

1. Assessment and Planning:

   • Understand your existing TFS environment, including source code repositories, work items, builds, and other relevant configurations.
   • Identify the reasons for migrating to Azure DevOps and the expected benefits.
   • Plan the migration timeline, taking into consideration any downtime or impact on ongoing projects.
   • Decide which TFS projects/collections will be migrated to Azure DevOps and which can be left behind.

2. Setting Up Azure DevOps:

   • Create an Azure DevOps organization if you don’t have one already.
   • Configure projects, teams, and permissions in Azure DevOps to mirror your existing TFS structure.
   • Set up source code repositories, work item types, fields, and other configurations in Azure DevOps.

3. Data Migration:

   • Migrate source code repositories using tools like git-tfs, git-tf, or direct Git repository migration.
   • Migrate work items using Azure DevOps Migration Tools or similar third-party migration tools. This involves mapping fields, states, and workflows between TFS and Azure DevOps.
   • Migrate test plans, test suites, and test cases if applicable.
   • Migrate any build and release pipeline definitions.

4. Verification and Testing:

   • Validate that the migrated source code compiles and functions correctly in Azure DevOps.
   • Ensure that work items, attachments, links, and other data have been accurately migrated.
   • Test build and release pipelines to ensure they work as expected in Azure DevOps.

5. Training and Communication:

   • Provide training to your team members on how to use Azure DevOps effectively.
   • Communicate the migration plan, timeline, and potential disruptions to all stakeholders.
   • Address any concerns or questions from team members.

6. Final Migration and Cut-Over:

   • Perform a final data migration to capture any changes made after the initial migration.
   • Temporarily lock down TFS to prevent new changes while the final migration is being completed.
   • Perform the cut-over by pointing your team to start using Azure DevOps for all new work and changes.

7. Post-Migration Tasks:

   • Double-check that all data has been successfully migrated and is accurate.
   • Verify that build and release pipelines are working as expected in Azure DevOps.
   • Address any issues or discrepancies that arise during the initial usage of Azure DevOps.

8. Monitoring and Support:

   • Monitor the usage of Azure DevOps and provide support to team members as they adapt to the new environment.
   • Continuously gather feedback and make adjustments as needed.

Remember that the migration process can be complex and might require custom scripts or tools based on your specific setup. It’s crucial to thoroughly plan and test the migration to ensure a smooth transition for your development teams. Additionally, Microsoft’s official documentation and community resources can provide more detailed guidance tailored to your migration scenario.