SuSE SLES 11 and 12 AMIs use AWS specific repositories to install and update packages.
There are situations when SuSE systems aren't able to install new packages or update them because they lost their AWS repository configuration.
This problem can be fixed by issuing the following command as super user:
Disclaimer: This command will perform major changes to your system. Handle it with care and consult the SuSE documentation upfront!