Thanks t-p,
I can’t log in so I tried FTP.
I have removed all plugins and still had the problem. I even had some more lines describing new error so I put back this plugin (wp-super-cache) and came back to the original error message.
I have removed all themes and reinstalled twenty twenty. Doesn’t solve the problem.
What to try next? Is there a way to reinstal the old version of wordpress by FTP and do you think it could solve my problem?