It sounds like your computer is crashing during shutdown.
Kernel Panic Reports are stored at:
/Library/Logs/DiagnosticReports
If you copy and paste that string into:
Finder > Go menu > Go to Folder
it will take you to where those reports are stored.
They are named with Date&Time and start or end in ‘panic’
If you find one, please post the entire report here, by using the “additional text” Icon in the reply footer (looks like a paper with writing).
Please don’t post more about 20 lines of any other types of reports — they are interminable, and any information useful for this purpose is on the first screenful.
There are three quick take-aways from any panic report.
1) The panic-reason,
2) the extensions present at the "scene of the crime", and
3) the BSD process in which the problem occurred.
One more item that is important is the names of any third-party Extensions you have added. They are shown FIRST in the extensions loaded section
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Take look at your other reports. What you are trying to determine is whether there is a TREND.
Case A) There is a trend: This same panic occurs in each case, with the same extensions present, in the same BSD process. A trend can indicate corrupted software or a Hardware problem that can be tracked down and solved.
Case B) There is a decided NON-Trend. The panics occur "all over the Map" for different panic reasons and in different BSD processes, with different extensions present.
A Non-trend suggests you may have RAM memory problems. MacOS slightly randomizes the load point of key routines on each startup, as a hedge against fixed-address attacks. This causes a marginal memory cell to move into different routines each time your Mac starts up.
If the above is just "word-salad" to you, just ask and Readers can explain a bit more.
