Issue apt update can't update anymore

[Nick Carter]

Server operating system version

ubuntu 24.04

Plesk version and microupdate number

Plesk Obsidian Version 18.0.71

Hello since some couple of days i am having troubles updating the server.
The apt update works fine, but when i go for the upgrade.....

apt upgrade
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Calculating upgrade... Done
The following packages were automatically installed and are no longer required:
alt-python311 alt-python311-libs alt-python311-pip-wheel alt-python311-setuptools-wheel libapache2-mod-php7.4 php-common php7.4-cli php7.4-common php7.4-json php7.4-opcache
php7.4-readline
Use 'apt autoremove' to remove them.
Get more security updates through Ubuntu Pro with 'esm-apps' enabled:
libmagickcore-6.q16-7t64 liburiparser1 imagemagick-6-common
libmagickwand-6.q16-7t64
Learn more about Ubuntu Pro at Ubuntu Pro | Ubuntu
The following packages will be upgraded:
linux-firmware
1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 standard LTS security update
Need to get 537 MB of archives.
After this operation, 171 kB of additional disk space will be used.
Do you want to continue? [Y/n]
Ign:1 Index of /ubuntu noble-updates/main amd64 linux-firmware amd64 20240318.git3b128b60-0ubuntu2.17
Ign:1 Index of /ubuntu noble-updates/main amd64 linux-firmware amd64 20240318.git3b128b60-0ubuntu2.17
Ign:1 Index of /ubuntu noble-updates/main amd64 linux-firmware amd64 20240318.git3b128b60-0ubuntu2.17
Ign:1 Index of /ubuntu noble-updates/main amd64 linux-firmware amd64 20240318.git3b128b60-0ubuntu2.17
Err:1 Index of /ubuntu noble-updates/main amd64 linux-firmware amd64 20240318.git3b128b60-0ubuntu2.17
500 Internal Server Error [IP: 91.189.91.82 80]
E: Failed to fetch http://security.ubuntu.com/ubuntu/p...re_20240318.git3b128b60-0ubuntu2.17_amd64.deb 500 Internal Server Error [IP: 91.189.91.82 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

i gues that internal server error doesn't belong to my infrastructure. Previously i have never had any issue on this procedure....

Any hints?

ty.
Nick