Invalid time could cause your server (or probably your virtual server or docker instance) to be unable to use Ubuntu’s packaging system apt. It is a typical thing if your virtual or docker instance does not use automatic time synchronization.
It is really important even small installation and virtualized environments to have automatic time synchronization or the service they provide could become error prone with time!
The “apt” just reports the repositories are not valid yet:
myuser@my-server-pc:~$ sudo su root@my-server-pc:/home/myuser# apt update Hit:1 http://archive.ubuntu.com/ubuntu bionic InRelease Get:2 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB] Get:3 http://archive.ubuntu.com/ubuntu bionic-backports InRelease [74.6 kB] Get:4 http://archive.ubuntu.com/ubuntu bionic-security InRelease [88.7 kB] Reading package lists... Done E: Release file for http://archive.ubuntu.com/ubuntu/dists/bionic-updates/InRelease is not valid yet (invalid for another 151d 18h 5min 59s). Updates for this repository will not be applied. E: Release file for http://archive.ubuntu.com/ubuntu/dists/bionic-backports/InRelease is not valid yet (invalid for another 151d 17h 16min 26s). Updates for this repository will not be applied. E: Release file for http://archive.ubuntu.com/ubuntu/dists/bionic-security/InRelease is not valid yet (invalid for another 151d 17h 15min 3s). Updates for this repository will not be applied. root@my-server-pc:/home/myuser# date Thu Jan 17 15:11:56 UTC 2019
The clock shows 17 January 2019, but now is 18 June 2019! This is a Ubuntu virtual server with the minimal installation.
The solution is to synchronize your clock manually or use a service (the better way)!