Warnings by sudo apt update

[amir]

Helllo,

when i do an update i get the following warnings. Can someone tell what these are about and help repair them?

Code Select Expand

amir@sparky:~$ sudo apt update
Hit:1 http://www.deb-multimedia.org buster InRelease
Hit:2 http://deb.debian.org/debian buster InRelease                           
Hit:3 http://ppa.launchpad.net/kxstudio-debian/libs/ubuntu bionic InRelease   
Hit:4 http://deb.debian.org/debian-security buster/updates InRelease           
Hit:5 http://deb.debian.org/debian buster-updates InRelease                   
Hit:6 http://ppa.launchpad.net/kxstudio-debian/music/ubuntu bionic InRelease   
Get:7 https://repo.sparkylinux.org core InRelease [3.586 B]                   
Get:8 https://repo.sparkylinux.org stable InRelease [6.540 B]                 
Ign:9 https://kx.studio/repo stable InRelease                                 
Ign:10 https://kx.studio/repo gcc5 InRelease                             
Hit:11 https://kx.studio/repo stable Release       
Hit:12 https://kx.studio/repo gcc5 Release                   
Hit:13 http://ppa.launchpad.net/kxstudio-debian/plugins/ubuntu bionic InRelease
Hit:14 http://ppa.launchpad.net/kxstudio-debian/apps/ubuntu bionic InRelease
Hit:15 http://ppa.launchpad.net/kxstudio-debian/kxstudio/ubuntu bionic InRelease
Err:7 https://repo.sparkylinux.org core InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 5CA76B26C40956B8
Fetched 10,1 kB in 6s (1.593 B/s)                                             
Reading package lists... Done
Building dependency tree       
Reading state information... Done
All packages are up to date.
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://repo.sparkylinux.org core InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 5CA76B26C40956B8
W: Failed to fetch https://repo.sparkylinux.org/dists/core/InRelease  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 5CA76B26C40956B8
W: Some index files failed to download. They have been ignored, or old ones used instead.


[pavroo]

Check here:
https://forum.sparkylinux.org/index.php/topic,5188.msg13705.html