Edit: To summarize, I purged the packages and installed python3.10 as a new package. According to others who followed this, you do not need to remove and add the ppa as I did. I am removing that from the answer. It has also been suggested that merely forcing the install with sudo apt install -yf has worked when this issue came up in past versions. I can't verify because I did the following instead:
I had installed Python 3.10 using deadsnakes.
The issue and solution are described here:
libpython3.10-minimal and libpython3.10-stdlib fail to install #207
I ran the suggested command (explained in more detail at the end of this answer):
sudo apt --fix-missing purge $(dpkg -l | grep 'python3\.1[01]' | awk '{print $2}')
This prompted with:
The following packages will be REMOVED: idle-python3.10*
libpython3.10-minimal* libpython3.10-stdlib*
libpython3.10-testsuite* python3.10* python3.10-distutils*
python3.10-examples* python3.10-full* python3.10-gdbm*
python3.10-lib2to3* python3.10-minimal* python3.10-tk*
python3.10-venv*
Note that there may be other packages removed with this command.
As suggested, I ran:
sudo apt --fix-broken install
There wasn't anything to fix because it had been purged.
Next I went ahead and upgraded unrelated packages before continuing:
sudo apt upgrade
At this point, running python --version showed it had rolled back to Python 3.8.10. I want Python 3.10 again so I ran:
sudo apt install python3.10
This prompted with:
The following additional packages will be installed:
libpython3.10-minimal libpython3.10-stdlib python3.10-minimal
Suggested packages: python3.10-venv The following NEW packages will
be installed: libpython3.10-minimal libpython3.10-stdlib python3.10
python3.10-minimal
The new install was a success!
Explanation For Cautious Beginners
The command used for purging python3.10 packages was:
sudo apt --fix-missing purge $(dpkg -l | grep 'python3\.1[01]' | awk '{print $2}')
The description of --fix-missing is found in man -apt-get:
Ignore missing packages; if packages cannot be retrieved or fail
the integrity check after retrieval (corrupted package files), hold
back those packages and handle the result. Use of this option
together with -f may produce an error in some situations. If a
package is selected for installation (particularly if it is
mentioned on the command line) and it could not be downloaded then
it will be silently held back.
purge:
purge is identical to remove except that packages are removed and
purged (any configuration files are deleted too).
For the package names, a command substitution is used.
dpkg -l package-name-pattern...:
List packages matching given pattern.
Because no pattern was given for dpkg, a list of all installed packages is returned. In lieu of a pattern, the list is piped into grep so we can used the pattern 'python3\.1[01]' to narrow the list down to installed python3.10 packages. These results are then piped into awk '{print $2}'.
awk '{print $2}':
To put it simply, this awk a pattern scanning command. Here it returns only the package name from each line in the list. To better understand, run these commands together and observe the output:
dpkg -l | grep 'python3\.1[01]' | awk '{print $2}'
This should output a list of all of installed python3.10 package names, such as:
libpython3.10-minimal:amd64
libpython3.10-stdlib:amd64
python3.10
python3.10-distutils
python3.10-lib2to3
python3.10-minimal
python3.10-venv
The end result is the same as if you had entered all python3.10 packages yourself:
sudo apt --fix-missing purge libpython3.10-minimal:amd64 libpython3.10-stdlib:amd64 python3.10 python3.10-distutils python3.10-lib2to3 python3.10-minimal python3.10-venv
Now the system should be ready for a new install of python3.10.
