Am told I cannot create tag - I am not trying to create a tag

Question

Trying to change my question

https://superuser.com/questions/1161441/chrome-switches-tab-unexpectedly-with-a-noise

to

OS: Mac OSX 10.12.2 Browser: Chrome 55.0.2883.95 (64-bit)

I am in one tab - for example writing a comment or answer in StackOverflow when out of the blue with a tweety sound, "chrome://apps" page replaces the page I am on.

Is it some kind of key/mouse/swipe combo I have not noticed that I do with my magic mouse?

on a bountied question, I am told I need 300 points to create the tag macos - I am doing no such thing.

Please help me update my question

Answer 1

It looks like a tag synonym that got reversed earlier today is the cause.

New edits to questions will trigger the synonym rename and, as the existing tag has no questions, fail with the warning you are seeing.

For now I have retagged your question with macos and as a side effect created the tag in question.

Answer 2

The tag macos does not exist. It is, however, a synonym of the tag osx. OSX and macOS are functionally the same hence the tag association.