When trying to make a UNIQUE constraint, pgAdmin 4 got confused and couldn't continue just because my field name contained a space. For some absurd reason, it doesn't add the quotes around identifiers and thus breaks for anyone who doesn't code with 1970s-era, US-centric name conventions. It displayed it to me as "stuff%20whatever" when the name was "stuff whatever".
I was forced to figure out how to do it in raw SQL.