Background syntax check freezes in PyCharm, what to do?

Question

PyCharm

I open my project in PyCharm and start working.
At first, everything is fine - he runs through the script, checks, underlines, etc.
I am writing a new one - it also checks "on the fly", underlines, removes underlining, when I correct it - in general, everything is fine.
At some point, the background checker breaks (and this always happens after a while).
For example, I started writing start = 1, but when I wrote sta, it broke.
And above this line it writes unresolved reference 'sta', although it has long since written start and beyond.
On other lines - there was some kind of error on this line, corrected - and he still writes the old error.
And this lasts until you restart everything (the whole PyCharm, just closing / opening the current file does not help). That is, you write code, and the checker starts to dislike everything that you write (although you write correctly, at startup everything works correctly). As a result, the entire code is underlined in different colors somewhere, highlighted with different backgrounds somewhere, and it looks terrible.
How to make sure that this does not happen, or at least what to click on so that it starts checking normally again in the background? (Looked for the menus - did not find).
PyCharm Community 2019.2, windows 10.

Answer 1

java updated?