I have followed the thread trying to find a solution but it seems a lot of people are experiencing the same problem. I updated adobe reader to 16.09.20 and it has been crashing every few minutes. All i do is study my textbooks while highlighting. I have read several posts where your reply is "it's the documents that may have a problem". I have been reading this book on previous versions with no issues though.
I have read several posts, where the I observed the issue has not really been addressed. I use an ipad iOS 9.3.5.
We apologize for any inconvenience this issue has caused.
We have submitted an update that resolves the crashing problems introduced in 16.09.20 and we are awaiting approval from Apple.
We appreciate your patience.
Acrobat Reader 16.09.21 is available in the App Store now.
It should resolve the frequent crashes that you have experienced.
Please give it a try and let us know if it works for you.
We apologize for the inconvenience.