I'm using Debian Stretch 9.x.x, and the KDE desktop.

I normally run "apt-get update" before installing new software, but this is
the error I keep getting for the past week when I run "apt-get update"::

Err:7 http://mirror.picosecond.org/debian stretch/updates/main Sources
404 Not Found [IP: 184.105.204.138 80]
Ign:8 http://mirror.picosecond.org/debian stretch/updates/contrib Sources
Ign:9 http://mirror.picosecond.org/debian stretch/updates/main all Packages
Ign:10 http://mirror.picosecond.org/debian stretch/updates/main amd64 Packages
Ign:11 http://mirror.picosecond.org/debian stretch/updates/main Translation-en_US
Ign:12 http://mirror.picosecond.org/debian stretch/updates/main Translation-en
Ign:14 http://mirror.picosecond.org/debian stretch/updates/main amd64 DEP-11 Metadata
Ign:15 http://mirror.picosecond.org/debian stretch/updates/main all DEP-11 Metadata
Ign:16 http://mirror.picosecond.org/debian stretch/updates/main DEP-11 64x64 Icons
Ign:18 http://mirror.picosecond.org/debian stretch/updates/main DEP-11 128x128 Icons
Ign:21 http://mirror.picosecond.org/debian stretch/updates/main amd64 Contents (deb)
Fetched 110 kB in 3s (30.9 kB/s)
Reading package lists... Done
W: The repository 'http://mirror.picosecond.org/debian stretch/updates Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: http://ppa.launchpad.net/giuspen/ppa/ubuntu disco InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY B8668B055FE1EFE4
W: The repository 'http://ppa.launchpad.net/giuspen/ppa/ubuntu disco InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://mirror.picosecond.org/debian/...source/Sources 404 Not Found [IP: 184.105.204.138 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.


Everything I have found that says here's how to fix this problem has not work.
Is there a fix for this, if so where, and besides reinstalling the whole system again?

what is a 404 not found error?
btw, you can't "fix" that error.
try to open that link in your browser, what do you get?
exactly.
so you need to edit your apt sources to reflect what is actually available.

ondoho,

I can compare your post to the teacher who is teaching a classroom of students, and states at some point: you know what I'm thinking and there's a test at the end of the day.

~~~~~~~~~~~~~
For over a week I've posted on the Internet what you see here in my post, looking for answers and absolutely got nowhere. After hitting the wall continually I felt I'd go to God's country and maybe find an answer, but......

Wow, if I were able to answered your question
- "what is a 404 not found error?",
- and knowing that "I can't fix that error",
- and knew that I needed to find another Debian mirror,
- and that I needed to edit my apt sources,
I would have know better to have come here thinking I would receive some useful help!

So, being the person that I am.... I'll just blow it all off, to the fact that it was late and maybe tired when you made the post, and that I am reading more into your reply than what is there, and say thank you for taking the time to read my call for help! Thank you!sh

you're telling me that
- you have now learned what a 404 error is - that surely is a good thing, no?
- you have also learned how to solve your problem, i.e. edit your apt sources, but instead of finding out how to do that, you sent me a long & elaborate reply where you are trying to interpret my feelings toward you?

how about we stick to the facts instead:
https://www.startpage.com/do/dsearch...it+apt+sources
unsurprisingly, the first result points to debian wiki, which is part of what i'm trying to say here.
have a good look at the 404'd link apt constructed, and how it relates to your sources.list.

PS:
i guess i could say the same thing about you, yes?

PPS:
oh, it is marked SOLVED already.
i understand you don't want to share it with me, but you should share your solution here, publicly, just like you asked the question.
because others, who search before asking, will benefit.