[SOLVED] Upgrade problem ?

[Didier B]

Having done this many times (and again on Friday), it appears that the problem is at your installation.  Bad internet, bad chip, bad power, or failure to allow to get to completion.  It also should take less than an hour, so perhaps your internet is the issue. 

I don't think so. My Internet is working quite well with exception of accessing Raspberry servers. I had no problem to install Stretch on a couple of Raspberry, though the access to the raspberry servers was long also, same as for the update & upgrade processes ...

The repetition of the same problem (around serverK) 6 times, after repeating 6 times the same process "by the book" excludes 'de facto' a mysterious random transitory fault in My Internet access, or in My power unit or in My power cable, or on My both RPis, or My four TF cards, may be  it is due to My Raspi box ...
Really, 40 years of experience as an electronics & IT engineer tell me this simply cannot be the case ...  

Ah, and yes, I got the message "press Enter to reboot" - at the end of each of the 6 attempts !