Android Studio 3.0 cannot resolve symbol Theme

Question

As stated in style.xml, there is a weird error, which shows Cannot resolve symbol \'Theme\', which is quite strange.

See pic of the error :-

My Project Spe

Answer 1

It seems to be a setting update of "injected references". Search this word in settings dialog and change its "Severity" option to a different value and apply, then change back to its original choice. The error highlight in the editor then disappears.