Today I was unable to rename a page. It was trying to insert into the logging table but that failed because log_id is NOT NULL but no default was set. I suspect it was caused by the same thing as my comment above, the wrong schema making some updates fail. (I rarely move pages, so I wouldn't notice until now.) The fix was this:

Solved: In my case, several sequences, functions, and a type where in schema "mediawiki" while the rest was in schema "public". I moved everything to "public" and the update script worked perfectly. Example commands:

I am seeing this error upgrading from 1.27 LTS to 1.31 LTS. PHP 7.2, PostgreSQL 9.6.14.