I go to screenshot by swipe or buttons and my phone comes up with 'system UI has stopped notification and doesn't take a screenshot. I have to press okay then the message repeats another 5 times before it goes away. I have a samsung galaxy A3 (2015)
Welcome to the forum. Messages like this are very difficult to troubleshoot because they may be caused by many things. I would suggest you reboot the phone a couple times and see if that helps. Next step would be a soft reset, I don't have an A3 but doing a Google for how to soft reset your model of phone should turn that up for you. Sorry that doesn't help much.
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