Random example:
That URL should be https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Wikibase/+/608433, not https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Wikibase/ /608433 (though the “space” URL also seems to work – Gerrit redirects it to the “plus” URL). This seems to have changed with the Gerrit 3.2 upgrade.