I'm using Ubuntu 20.04 and it worked fine for months now. yesterday I encountered this issue. When I update using GUI it says to check my internet connection. then I tried in terminal and it shows the following:
Hit:4 http://packages.microsoft.com/repos/code stable InRelease
Hit:6 https://dl.yarnpkg.com/debian stable InRelease
Get:1 http://ro-mirrors.evowise.com/ubuntu focal InRelease [611 kB]
Get:2 http://ro-mirrors.evowise.com/ubuntu focal-updates InRelease [611 kB]
Get:3 http://ro-mirrors.evowise.com/ubuntu focal-backports InRelease [611 kB]
Get:5 http://ro-mirrors.evowise.com/ubuntu focal-security InRelease [611 kB]
Hit:7 http://dl.google.com/linux/chrome/deb stable InRelease
Err:1 http://ro-mirrors.evowise.com/ubuntu focal InRelease
Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
Err:2 http://ro-mirrors.evowise.com/ubuntu focal-updates InRelease
Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
Err:3 http://ro-mirrors.evowise.com/ubuntu focal-backports InRelease
Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
Err:5 http://ro-mirrors.evowise.com/ubuntu focal-security InRelease
Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
Hit:8 http://archive.canonical.com/ubuntu focal InRelease
Reading package lists... Done
N: See apt-secure(8) manpage for repository creation and user configuration details.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
E: The repository 'http://ro-mirrors.evowise.com/ubuntu focal InRelease' is no longer signed.
E: Failed to fetch http://ro-mirrors.evowise.com/ubuntu/dists/focal/InRelease Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
N: See apt-secure(8) manpage for repository creation and user configuration details.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
E: The repository 'http://ro-mirrors.evowise.com/ubuntu focal-updates InRelease' is no longer signed.
E: Failed to fetch http://ro-mirrors.evowise.com/ubuntu/dists/focal-updates/InRelease Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
E: Failed to fetch http://ro-mirrors.evowise.com/ubuntu/dists/focal-backports/InRelease Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
E: The repository 'http://ro-mirrors.evowise.com/ubuntu focal-backports InRelease' is no longer signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://ro-mirrors.evowise.com/ubuntu/dists/focal-security/InRelease Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
E: The repository 'http://ro-mirrors.evowise.com/ubuntu focal-security InRelease' is no longer signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
Can sombody please help me to fix this issue. Thank you.