What version did you download? The latest release (yesterday, 3/21/17) is 6.4.10 and there are multiple reports of it crashing.... an update is likely to be issued soon (like today?) as that's been the pattern for a couple of months now. Daily updates until they get it somewhat stable....
Having a reliable messaging application is a must, COMMUNICATEPATTY. The application was recently updated to version 6.4.11 which has a fix for this issue. Please make sure your application is up to date by visiting Play Store on Android or App Store on iOS and check to see if your Messages + application is updated. Let me know if the issue persists.
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