pls help, i got 'License XML is invalid' Error...

I got ‘License XML is invalid’ error when I returned my license ,have you guys met this error before? does sb know how to resolve this ?

I am having the same problem.
I am using Unity 5.4.3 p4 on Mac.

I am getting this error on only one project

I’m getting this too. Window error message links to: FAQ which does not explain why any of us are getting the error message.

Guess this is Unity Team’s new business model. Pull the rug out from under its users to shake us down for more money.

Workaround: Switch to Unreal Engine.