Any idea why? I just went back there and they all started attacking me. No chance to pay a fine or go to jail, just a fight to the death. I've tried not fighting back and it doesn't do anything they just kill me.

I've done nothing to upset them, it just feels like another bug.

I'm honestly about done with this game as every time I start the game up to play for a while I just encounter one problem after another which is a shame, because I really want to enjoy it.

Are you a vampire?
Draw your weapon and then put it away, that should make the guards more cooperative

And check your crime stats. Did you do anything naughty somewhere in the hold? Maybe by accident?

I tried lots of stuff and nothing worked so I just killed loads of guards and eventually, completely randomly, they decided to try and arrest me so the problem got solved.

I still have no idea why it happened unless I did something by accident that I just didn't notice. A very strange episode.

Edit - No I'm not a vampire.

I had the same issue at one point. I believe it had something to do with the thieves quest. I didnt want to kill all the guards so I reloaded. Next time I went to Riften, I avoided that dude you meet when you first get there and didnt have the problem.

http://www.gamesas.com/topic/1331838-riften-goes-bonkers-and-spawns-hostile-stormcloaks/page__p__20035642#entry20035642 a while back, too. For future reference if it ever happens again, you can avoid the slaughter-fest by pickpocketing one of the guards at the guard towers outside and then having them take you to prison.

The only thing I can think of is that the game somehow thinks you've accrued a truly massive bounty in the Riften hold (enough to cause the guards to try to murder you on sight), even when you most likely very much haven't. My character never even committed so much as a murder, much less a crime spree that would result in that kind of bounty. (In fact, when it happened, she had no bounty whatsoever, and indeed never had.)

I find this whole guards thing very unbalanced it doesnt matter if your thane or dragonborn if you get an pounding they just keep staring or running like cowards and just let you get owned but too me it seems they did some changes with update 1.4 because i also use the pickpocket trick when i escape from jail but now they just say " I know you" and i cant get too pay my bounty so another solution may be too steal food in the inn and hope they dont switch too attack mode but instead paying the bounty

edit: Tyraa Rane are you wearing Elven Armour in Riften ? this could also initiate the encounter with the stormcloak