Termux upgrade fails: can't find archive

Yes, I had first tried it via apt… Meanwhile, I found, the culprit was, that I had tried to install python3-dateutil from a deb package, that I had from somewhere else. That had failed. I had [almost] forgotten about it. It had also left that package in a kind of half installed state - I had not noticed at the time. I found, that I could not remove it, until I used –force-remove-reinstreq. Now, it looks like, things work as expected again. I have not thoroughly verified that yet - but I believe it so far.