Ubuntu 21.10 ‘Impish Indri’ has just been released. If you are using Ubuntu 21.04, you should be provided the option to upgrade to Ubuntu 21.10.

However, this roll out will be gradual. This means not everyone will be notified about the availability of the new version immediately. It may take a couple of weeks before you see the upgrade option.
But what if you are itching to get your hands on Ubuntu 21.10 that comes with GNOME 40 and other new features? Do you really have to wait? The answer is no.
Upgrading to Ubuntu 21.10 from Ubuntu 21.04 right now
Here’s what you do. Open the Software & Updates application:

And make sure that you have set “Notify me of a new Ubuntu version” to “For any new version” under the Updates tab.

Now open a terminal and enter the following command to make sure that your system is updated:
sudo apt update && sudo apt upgrade
Once your Ubuntu 21.04 system has all the updates installed, run the update manager to look for development release (Ubuntu 21.10 in this case).
update-manager -d
It will open the Update Manager tool that looks for updates. Since you have already updated the system, it won’t find new updates to install. However, it will see that Ubuntu 21.10 is now available.

You can hit the upgrade button and follow the on-screen option to start the upgrade procedure. You should have good internet speed to download the 2 GB worth of updates. Make sure that your system stays connected to a power source during the upgrade.
Enjoy Ubuntu 21.10!
“Error: E:The package linux-headers-5.11.0-44-generic needs to be reinstalled, but I can’t find an archive for it.”
Now what? Every way I can think of to upgrade to 21.10 gives me this error message.
I get a message saying it failed to download repository information. Can you help me please?
That’s a very generic message.
In the terminal, type this command and then share the last 3 lines of the output please:
sudo apt update
Abhishek Prakash, I’m relatively new to Ubuntu and if it wasn’t for these terminal commands I would find it very difficult to get a good working computer. Thanks to people like you I don’t have to look very far.
Cheers, Paul
Glad to be of help in your Linux journey, Paul :)