Symptoms:
- I have a Pro license and I am trying to activate Unity in a different version.
- I would like to know which versions of Unity I can activate with the license I have.
- I would like to know if I can activate my license on previous versions of Unity.
- I see the error, 'Serial is not valid for the requested version of Unity.'
Resolution:
Unity subscription licenses and Unity Personal licenses can be used on any version of the Unity Editor.
However, legacy perpetual* licenses and 'pay-to-own*' licenses, are locked to a specific version of the Editor and under (backward compatible).
For example, if you have a legacy Unity 4.X license, you can activate any version of Unity 4, or Unity 3. Perpetual Unity 5.X licenses can be activated in all versions of Unity 5, 4, and 3.
Pay-to-own* licenses are tied to the most recent, stable version of the Editor when the license was converted. These licenses are backward compatible on all prior versions except LTS (Long Term Support) versions of the Editor.
If you have an old license and want to activate on a newer version, you need to purchase a new subscription license.
To use an older version of Unity, you can download the version you are looking for from the download archive.
More Information:
Subscription licenses can generally be used on all currently released versions of Unity. If your license isn’t working on an expected version, contact Unity Customer Experience.