In the case of Inventor for many years the migration effort has been rather low - often you didn't even have to touch your add-in, it just worked with the new release as well.
Every now and then, however, we introduce changes that require testing and even rethink of certain parts of the code.
One such big change was moving from LOD (Level Of Detail) in Inventor 2021 to Model States in Inventor 2022. The changes not only affected code directly working with LOD, but other parts too:
Porting guide from Level of Details to Model states
Now we had another one: moving from .NET Framework 4.8 in Inventor 2024 to .NET 8 in Inventor 2025 - other products like Vault did the same.
If you are relying on libraries that do not work with .NET 8, that can be a problem.
It's worth checking, however, if your existing .NET Framework 4.8 add-in works with Inventor 2025 - it might, which could give you some extra time to migrate.
Autodesk Desktop API Updates: .NET Core 8.0 Migration | Webinar recording
Autodesk Vault 2025 SDK – Breaking News
If you are going from Inventor 2021 (or before) to Inventor 2025 you'll have to deal with both changes at the same time, which could be a big effort.
The bottom line of all the above is that Inventor developers should be testing their add-in in the latest versions, and don't just assume or hope that things will work.
You can get ahead of things by testing your add-in with Inventor betas and release candidates available on the feedback site, months before the final product is published.
In general with Autodesk add-in and plug-ins it's very important to plan for migration activities before rolling out the tools in a large production environment. Without adequate testing in a "sandbox" environment, you can end up with incompatibilities and other issues after the rollout.
The API documentation contains a What's New section that can be a good starting point when migrating to the new release. In the case of Inventor 2025 you can find it here.
You can find the same for Vault 2025 here - if you have developed solutions for that, those too should be tested for each new release.
If you're an ADN member then you can get additional licenses for development purposes at no extra cost which could also be useful to create a dedicated testing environment.