Re: To PostgreSQL in Debian
> With the end of LTS support for Debian stretch, we are no longer
> supporting stretch on apt.postgresql.org.
>
> https://wiki.debian.org/LTS/
>
> stretch-pgdg has been copied to apt-archive.postgresql.org and will be
> removed from apt.postgresql.org at the end of October 2022.
The files have been removed now.
If you still need stretch, the files are on apt-archive now:
deb https://apt-archive.postgresql.org/pub/repos/apt stretch-pgdg main
No new packages will be added to that repository.
Christoph