Autodesk Platform Services (APS) is upgrading the Revit Automation engine to Revit 2026.5 and .NET 10 on September 21, 2026. This update will change the underlying Revit and .NET runtime environment used by Revit Automation applications.
For BIM teams, developers, engineering consultants, and organizations using automated Revit workflows, this is an important update to prepare for. While Autodesk expects most existing AppBundles to continue working, compatibility testing is recommended before the production migration.
What Is Changing?
The Revit Automation environment will move from the existing Revit 2026 version to Revit 2026.5. At the same time, the underlying runtime will be upgraded to .NET 10.
Autodesk has indicated that the earlier Revit and .NET environment will not be maintained after the migration for security reasons.
The key changes include:
- Revit Automation engine upgraded to Revit 2026.5
- Runtime environment upgraded to .NET 10
- Production migration scheduled for September 21, 2026
- Existing AppBundles are generally expected to continue working
- Applications with runtime-specific or third-party dependencies should be validated
Do Existing AppBundles Need to Be Updated?
For most applications, an immediate AppBundle update is not expected to be necessary.
However, applications can behave differently when their underlying runtime environment changes. This is particularly relevant when an AppBundle depends on third-party .NET libraries, external SDKs, native dependencies, or specific runtime behavior.
Rather than rebuilding every application, developers should first test their existing AppBundles with Revit Desktop 2026.5.
What Should Developers Validate?
A compatibility check should cover the complete automation workflow, not just whether the AppBundle launches successfully.
Developers should verify:
- AppBundle loads correctly
- Revit API calls function as expected
- Transactions and document operations work correctly
- Model processing produces the expected results
- Third-party libraries are compatible with .NET 10
- External dependencies continue to work
- Generated models and files are correct
- No unexpected errors occur during automation
Testing representative project models can also help identify issues that may not appear during basic application startup.
Testing Revit Automation Locally
Autodesk recommends using its Revit Automation local debugging workflow to run and validate AppBundles with Revit 2026.5.
Local validation allows developers to identify compatibility issues before the production environment changes. If an issue is found, the affected dependency or application code can be updated, followed by another round of testing.
This approach can reduce the risk of unexpected interruptions to automated BIM workflows.
Why This Matters for BIM Teams
Revit Automation can support a wide range of digital engineering processes, including automated model processing, BIM quality checks, parameter management, data extraction, documentation, repetitive modeling tasks, and model validation.
As organizations increasingly adopt automated BIM workflows, maintaining compatibility between applications, Revit versions, and .NET environments becomes important for reliable project delivery.
Teams that depend on automation for multiple projects should therefore review their existing AppBundles and dependencies before the September 21 migration.
Key Takeaway
The upgrade to Revit 2026.5 and .NET 10 does not necessarily mean that every Revit Automation application needs to be rebuilt. Autodesk expects most existing AppBundles to continue working.
However, proactive testing is recommended—particularly for applications that use third-party .NET libraries or runtime-specific functionality.
By validating applications with Revit Desktop 2026.5 and resolving compatibility issues before production migration, organizations can prepare their automated BIM workflows for the updated environment.
Conclusion
The Revit Automation upgrade is an important step in keeping Autodesk's automation environment current and secure. For BIM developers and engineering organizations, the best preparation is to validate existing applications, review dependencies, and test complete workflows before the migration date.
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Infromation From: https://aps.autodesk.com/blog/revit-automation-engine-upgrading-revit-20265-and-net-10-september-21-2026
