Upgrading from Mint 20.3 to 21.1

My wife informs me that a 21.1 Mint upgrade is available and I’ve read that it’s better to upgrade to 21 first. We have a small HP laptop to trial run any major things before we go and do it to her HP Envy.

First, I’m not seeing clearly how to clear the cache as I’m instructed to do so here: How to upgrade to Linux Mint 21 — Linux Mint User Guide documentation . That’s the first step it says to do. I’ve looked up guides to clear the cache through the terminal, but they are not clear where to do this. This link - Frequent question: How do I clear cache in Linux Mint?. says to go to an Activities panel. What? Where?

Well I decided to run the apt update and apt install mintupgrade commands anyway and got nowhere. This is what the error message said in terminal…

Hit:1 Index of /ubuntu focal InRelease
Ign:2 http://packages.linuxmint.com una InRelease
Hit:3 http://packages.linuxmint.com una Release
Get:4 Index of /ubuntu focal-updates InRelease [114 kB]
Get:5 Index of /ubuntu focal-security InRelease [114 kB]
Hit:6 Index of /ubuntu focal InRelease
Hit:7 https://brave-browser-apt-release.s3.brave.com stable InRelease
Hit:9 Index of /deb stable InRelease
Ign:10 http://download.opensuse.org/repositories/home:/Provessor/xUbuntu_20.04 InRelease
Get:11 Index of /ubuntu focal-backports InRelease [108 kB]
Err:12 http://download.opensuse.org/repositories/home:/Provessor/xUbuntu_20.04 Release
404 Not Found [IP: 2001:67c:2178:8::13 80]
Reading package lists… Done
E: The repository ‘http://download.opensuse.org/repositories/home:/Provessor/xUbuntu_20.04 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.

I have no idea what all this means. Could someone help me understand what i need to do to upgrade? I thought running apt update was a straightforward process.

We don’t use this little laptop much, just as a second laptop at a table for simple lookups, and we try to run updates somewhat often, but now we appear to be hung up.

I’m very new to Linux, but saw the news myself and decided to check it out. I ran updates as normal, rebooted and had a pop up that the upgrade was available. Went ahead and installed and have had no difficulties.

This is the first upgrade release since 20.3, so you’re fine.

Try sudo apt-get update && sudo apt- get upgrade -y Follow here: How to Upgrade Linux Mint 20.3 to Linux Mint 21

I found out that the repository called “opensuse” was no longer available near the end of the message above at “E:”, and someone on another board informed me I had to open Software Sources and remove it. That took care of it. I was able to run an update normally.