Google Ads: Could not find the entity?

I want to launch a Google Ads campaign thru campaign draft I made last year, but I keep getting ambiguous "Could not fine the entity" error: https://www.dropbox.com/s/2503w8u5djusz73/google-ads-error-screenshot-2.jpg?dl=0

The "Fix it" button leads to languages, but going there doesn't really give any ways to fix the problem.

Help?