AWS EC2 Linux Instance Cannot use "yum update"

Security groups and routing and all the rest of it are fine, because the yum command is able to go out and talk to the repos, identify the packages that it wants, and tries to download them.

Long-story-short - there's a utility called /usr/libexec/urlgrabber-ext-down that's key here, and it is either missing or it's set use a version of Python that is no longer on your system.

The official Red Hat solution (I know you're not running RHEL but it's very similar) is here https://access.redhat.com/solutions/5360161 (you need a login to view it).

Your exact issue is discussed in depth here https://unix.stackexchange.com/questions/355073/cannot-yum-install-any-packages

The solution boils down to one of either

• does /usr/libexec/urlgrabber-ext-down exist? If it does then check first line of it (the #! entry) which should be something like #!/usr/bin/python. Does this (/usr/bin/python in this example) actually exist?

• if /usr/libexec/urlgrabber-ext-down doesn't exist (or is a symlink pointing to a non-existent file) then recreate it ls -l /usr/libexec/urlgrabber-ext-down*. And then depending on the output ln -s /usr/libexec/urlgrabber-ext-down-[version] /usr/libexec/urlgrabber-ext-down