The repository 'http://packages.linuxmint.com ulyssa InRelease' is no longer signed.

[ODTech]

Did you try post#16 ?

I am experiencing the same error with Linux mint 20.2. I have tried lots of commands but nothing help. Can someone please assist.
E: Failed to fetch http://packages.linuxmint.com/dists/uma/InRelease 403 Forbidden [IP: 91.241.95.156 80]
E: The repository 'http://packages.linuxmint.com uma InRelease' is no longer signed.

Thanks Naas

Install cloudflare Warp like @ponder suggested. They have a deb installer now so it's easy to get up and running.

https://pkg.cloudflareclient.com/

Once installed you have to register and then connect when you want to use it.

warp-cli register

warp-cli connect