Raspberry pi update issue

Question

i have recently flashed latest OS in my raspberry pi.When i try to use " sudo apt-get update" in my raspberry pi 3 B, i am getting the following error

Hit:1 http://raspbian.raspberrypi.org/raspbian bullseye InRelease              
Hit:2 http://archive.raspberrypi.org/debian bullseye InRelease                 
Ign:3 http://packages.ros.org/ros/ubuntu bullseye InRelease                    
Err:4 http://packages.ros.org/ros/ubuntu bullseye Release
  404  Not Found [IP: 64.50.236.52 80]
Reading package lists... Done
E: The repository 'http://packages.ros.org/ros/ubuntu bullseye Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

Kindly help me to solve the issue

Answer 1

You asked, "Kindly help me to solve the issue"

What is always the best way to resolve any issue is to do some research on your own before asking questions here. As the comment from @joan suggested, your problem appears to be that you have changed/modified your list of sources. For the Raspberry Pi OS (aka raspbian), your sources lists are typically housed in two files:

/etc/apt/sources.list
/etc/apt/sources.list.d/raspi.list

If you are using another OS, you should first determine where your source lists are located. You should also review those source lists, and make sure they are correct. From the scant information in your question, it seems there are issues - perhaps you changed something, but didn't research your change well enough??

Your question also lacks essential information that makes it difficult for anyone to help you. Specifically, you haven's stated what OS you are using! For example, if you had stated that you were using RPi OS (formerly known as raspbian), we could tell you what your source list files should have in them - without that, we can only guess at an answer that might help you. That said, here are some things you should read to "help you solve the issue":

• Identify what OS you are trying to install/update.

• Peruse the system manuals for apt (man apt), and sources.list (man sources.list). Keep these system manuals in mind for future issues that may arise - or just to increase your knowledge of "how things work."

• If you are going to edit your sources lists in a distribution based on Debian, this URL has useful information.

• Should I use apt or apt-get?. This article from HTG in particular has some information to consider.

Armed with all of this, you may be able to solve your issue yourself. If not, hopefully this will help you edit your question so that you may get the answers you need.