This issue pops up from time to time, and I can see questions about it on Facebook groups. So, to help you a little, here is this short post 🙂
When trying to update Oxygen, you got this error:
Go to the Oxygen Settings page and switch to the License tab:
Make sure that your license is valid. Now, once you are here, click “Save Oxygen License”. No need to re-enter it. Just click the button and wait for the page to reload.
Now you can go to the plugins page and click Update again. It should now work properly.