Why can't I build to Unity Web Player from a patch release?

Symptoms

• I am using a new patch release, but I cannot update Web Player.

Cause

If you are trying to load a Web Player build from Unity after recently updating to the latest patch release, you may receive this error message:

"Failed to update Unity Web Player"

Resolution

You cannot build and release a Web Player game with a patch release, as the runtime will not be updated with patch versions.

It is recommended that you create a Web Player build using the latest official Editor patch release instead.

More Information

You can find out more information about the specific bugs fixed in each patch release by looking at the Unity QA patch releases archive here