I am getting an error "Notice: Undefined index: distribution_name in drupal_install_profile_distribution_name() ". How do I fix this?
After seeing the results of drupal_get_profile() and querying for that value in the system table, the result of the query showed that the profile's files were (supposed to be) in:

/var/www/html/profiles/[profile name]/


However, that folder path did not exist. Since Drupal could not find the profile's files in that folder path, it could not set a distribution_name.

I found the correct profile files in my original download from way back in the day, re-uploaded them to the correct directory on my server and cleared the cache. The message disappeared.