How long is an open bag of brown sugar good for?

I've used brown sugar that was WAY older than that, and nothing 'bad' happened. It was and still is in rubber sealed top glass jar, though.

I've used some that was 5 years old in a cake and it was fine.

Sugar IS a preservative. Like salt is as well. It's when it's wet or damp that bacteria or mold will grow.

Mine last forever. You can put a piece of bread in the container if it gets hard.

Yeah.

We have sugar around much longer than that as we also rarely use it

I'm no expert but sugars generally last forever. That's partly why those gross packaged cupcakes never expire.

No sell by date
Always good

6 months

Sugar last almost forever. It will be fine.

Of course it is!

It's fine

I believe it's still ok!

It might be hard as a rock

you should still be good, but was it opened and if so did it harden?

It last forever.. just keep it in a sealed container

It should still be good

It has a habit of absorbing moisture and becoming a brick!

Basically cyanide now.

Brown sugar is just coloured white sugar so same applies

Yes