This just happened to me. I opened a terminal window. Then in Finder, I went to Application>Messages, right click and select "Show Package Contents". Then Contents>MacOS, from there I dragged Messages executable on to Terminal window and hit Enter. The Messages app opened immediately. Closing Terminal window closed Messages app but after this it opened normally. I don't know why it worked and I don't know if it'll work for you, give it a shot.
PersyJack
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