When this occurs, is it just pamac that crashes or are you unable to open task manager and most all other system utilities, including add/remove programs? I think I might be experiencing the same issue, and have been for many months. I started a different thread here New pending updates break my system - #2 by andreas85 for mine. Just updated it with system logs today.
My issue was never noticed before hand. Id be doing w/e in the system tray and notice updates indicator. Id click on it and nothing. After this happened a few times, I began trying things before hard resetting (glad to know I have option now vs JUST a hard restart) and thats when I noticed that no system utilities would launch. Also, the start menu would work but clicking on restart, it would do nothing.
Im adding my comment to the thread in case it might assist a solution being found (assuming that it is the same bug)