Could not load list of meta packages: [Errno 12] Cannot allocate memory

Question

I use AWS free tier.
I've encountered the error message saying 'Could not load list of meta packages: [Errno 12] Cannot allocate memory' after apt-get upgrade error with the message 'fatal -> failed to fork'.
Does anyone know why I got these messages and how to solve the problem.
Thank you.

Could not load list of meta packages: [Errno 12] Cannot allocate memory

Answer 1

Actually, this prompt was written in file

/var/lib/ubuntu-release-upgrader/release-upgrade-available

so remove it and the error message will disappear. This file was created by

/usr/lib/ubuntu-release-upgrader/release-upgrade-motd

and if you don't deal with it, I think it will disappear after a day.