Quote from: ETFbitcoin on May 13, 2021, 09:57:17 AM

Since the debug.log doesn't show anything unusual & i notice that you're using Windows, you can try using "Event Viewer" software to find any error/warning around time when Bitcoin Core closed by itself.

If you never use it, check this guide https://www.howtogeek.com/school/using-windows-admin-tools-like-a-pro/lesson3/.

Thanks for your support, I will try my luck...

I really thought the latest BitcoinCore versions has a bug and someone might have the same problem or can tell what exactly is the difference from latest to previous versions so this problem could occur.
Can't imagine that it is due to my hardware or SW, since the problem is only with the incoming transactions from Nicehash and that only since Januar this year and since v0.21.0. This is for sure because if I re-syncronize the entire chain with latest BitcoinCore Version, it runs through all the years (many transaction over the past 4 years also incom from NH) until Januar 2021 without any problems and then always crashes on the same transaction from Nicehash dad0f505c7c9697e1b7b79ecc7133701fd0a4424993ec27770191bfb6a290763 (as in my first post). Then I revert to v0.20.1, sync this transaction (no problem), after that revert again to v0.21 and run until next transaction from Nicehash with same problem...
Maybe it has really to do with the size of transactions, because those from Nicehash are much larger than other, 7MB compared to usually a few hundred kb.
Now running with previous v0.20.1 and it works like a charm without any problems.