Is the following sentence missing commas? If so where?: You will not be able to get in unless I accidentally left a door unlocked.
By AP style needs not.
This is a complex sentence and before dependent clause you need not any COMMA.
But by Cambridge or the British grammarians somewhere use a COMMA before dependent clause too. Like unless is a connecting word for the dependent clause.
Personally, I use AP style as it is a wide spread in the world.