Error badge in IDE

Suddenly I got this badge in IDE:

Everything compiles cleanly, yet still IDE shows me this and an error message “Arduino.h: No such file or directory at line 1 col 21”. Restarting IDE does not change anything, the badge and message reappears upon 1st project save.

Do you have the same issue on other projects?

Yes but it’s false alarm, hit “Rebuild project index” and it’s gone.