I didn't actually "fix" it as it still happen sometimes. In my case it was a matter of turning off and on BT and on one occasion doing a fast reboot. Overall the BT doesn't crash often and I have used it for music (BT headphones) and my smart watch. As an example yesterday it crashed 3 times in 5 minutes, did a restart and it ran just fine the rest of the day. Today it hasn't had a problem at all pairing devices and using both the headphones and separately the smart watch. Hope yours works as well for you!
2nd edit: BT force closing is becoming more of an issue. It is now very difficult to maintain a connection with my smartphone for more than a few seconds. Thinking seriously about a return to stock if a solution is not found as I use BT heavily. Everything else works fine so it would be a shame to loose I good ROM because of one simple but significant issue!
I'm using RR and that's what was happening for me as well. It would be good for a day or two, and then started happening again.
It just got another update last week and that got rid of the BT share f/c, but IMHO, BT is still causing some real issues that are kind of worse. Random reboots that get stuck in a boot loop. It hasn't happened at all for me for almost a week until yesterday. And it's happened four times since then. Also, my BT connection in my car is hit/miss. Seems good, but when I'm on a call, it will just drop and then return. Doesn't disconnect the call, just goes to the phone. But there is a 1-2 second spot when it switches where nobody hears anything on either end. Frustrating. And turning off BT in a call will usually force a reboot.
I'm thinking of trying CM13 "stock", because that thread seems to indicate that the nightlies from the last few nights don't have the issue anymore. But not sure.