I put off updating my phone (galaxy s6) for quite awhile...I hate updates because there always seems to be a new glitch somewhere. Anyways, I finally ran the update a day and a half ago. Phone seemed fine that evening and I could text (I have SwiftKey). Then the next day, midmorning, I got the same message all of you have been getting, "Samsung Keyboard has stopped working" midway through composing a text that continued to pop up whenever I went into an app that involved using the keyboard. It randomly resolved itself before I got out of class to start troubleshooting. Today, I got the error message again and it stuck around. I found this thread. It appears there are multiple ways to at least temporarily fix it. Someone on here suggested going to the keyboard settings and reselecting SwiftKey as the default. I tried that and then the problem was temporarily fixed, but as soon as I went to use emoji, the problem returned. I went to the keyboard settings again and found that Samsung keyboard had been switched back to default by itself. Next, I tried switching the default back to SwiftKey (like I did the first time), and in addition, I also went into the Samsung keyboard settings and reset the settings (even though Samsung isn't set as the default). This seemed to work, and I was able to use emojis in my text without it crashing. We will see if it works long term, but it seems to at least have temporarily solved the problem (and made me happy, because I do NOT want to do a factory reset if I don't have to).
So, in steps, this is what I did:
1. Settings> General Management> Language and Input> Default Keyboard> SwiftKey Keyboard
2. Language and Input> Virtual Keyboard> Samsung Keyboard> Reset Settings
Hopefully this helps someone.