Ubuntu Bionic now failing to update

Hi, i’m running Ubuntu bionic minimal for more than a year now.
When I try to update now, an error about expired key is showing up:

rock@localhost:~$ sudo apt update
[sudo] password for rock:
Hit:1 https://downloads.plex.tv/repo/deb public InRelease
Hit:2 http://repo.linaro.org/ubuntu/linaro-overlay stretch InRelease
Hit:3 http://ports.ubuntu.com/ubuntu-ports bionic InRelease
Get:4 http://ports.ubuntu.com/ubuntu-ports bionic-updates InRelease [88.7 kB]
Get:5 http://ports.ubuntu.com/ubuntu-ports bionic-backports InRelease [74.6 kB]
Get:6 http://ports.ubuntu.com/ubuntu-ports bionic-security InRelease [88.7 kB]
Err:7 http://apt.96rocks.com/bionic bionic InRelease
Could not resolve ‘apt.96rocks.com
Fetched 252 kB in 20s (12.4 kB/s)
Reading package lists… Done
Building dependency tree
Reading state information… Done
63 packages can be upgraded. Run ‘apt list --upgradable’ to see them.
W: Failed to fetch http://apt.96rocks.com/bionic/dists/bionic/InRelease Could not resolve ‘apt.96rocks.com
W: Some index files failed to download. They have been ignored, or old ones used instead.