RE: https://lists.debian.org/debian-user/2017/08/msg01420.html
RE: https://lists.torproject.org/pipermail/tor-talk/2018-May/044171.html

This continues to be a problem in Tails 3.7.1 and in Debian when
configured with the .onion URLs. (and running Tor)
 
To quote the second URL above:
 
###
 
In Synaptic, when fetching new package lists:
 
Failed 0 B InRelease tor+http://vwakviie2ienjx6t.onion/debian/ stretch
InRelease
 
All of the other chosen entries are correct, but for some reason
this same error crops up every time and there is no apparent
workaround. Can someone please contact the admin behind this
and enable complete functionality for this URL+InRelease
 
THIS IS NOT A NEW ISSUE. This problem was first reported
to Debian's mailing list on Fri, 25 Aug 2017:
 
https://lists.debian.org/debian-user/2017/08/msg01420.html
 
The thread ended without any clear resolution. In addition
this problem was reported to several other areas of the web.
I don't know what it takes to find the person responsible
and get him to fix it.
 
####
 
I hope someone can fix this issue. Thanks.

And most recent: https://lists.torproject.org/pipermail/tor-talk/2018-June/044274.html
Topic: Tails: Failed InRelease - tor+http://vwakviie2ienjx6t.onion/