Cannot upgrade from Ubuntu 18.04 LTS to 20.04

I have tried to upgrade to Ubuntu 18.04 LTS to 20.04, however I get the following message:

Ign:18 bionic InRelease
Err:19 bionic Release
404 Not Found [IP: 80]
Reading package lists… Done
E: The repository ‘ bionic 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.

Can anyone help with this issue? Will appreciate any help.

Thanks in advance!

The website was not found. Remove the obsolete PPA, to get rid of this error.


Thank you very much. I did exactly that immediately after posting. Thought I’d give it a try. I removed all the PPAs and uninstalled a few software packages. I have installed Ubuntu 20.04 and its working fine.

Great to hear.
Please set @Akito 's answer as the solution, to help anyone else who might face this problem.