public key is not available

[PaulTimmermann]

Hey,

after installing OMV when i try to update(apt update) or to install anything this error comes.

Err:9 http://security.debian.org/debian-security buster/updates InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY AA8E81B4331F7F50 NO_PUBKEY 112695A0E562B32A
Err:11 http://httpredir.debian.org/debian buster-backports InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 04EE7237B7D453EC NO_PUBKEY 648ACFD622F3D138
Get:15 https://openmediavault.github.io/packages usul/main armhf Packages [6,220 B]
Reading package lists... Done
W: GPG error: http://security.debian.org/debian-security buster/updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY AA8E81B4331F7F50 NO_PUBKEY 112695A0E562B32A
E: The repository 'http://security.debian.org/debian-security buster/updates InRelease' is not 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.
W: GPG error: http://httpredir.debian.org/debian buster-backports InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 04EE7237B7D453EC NO_PUBKEY 648ACFD622F3D138
E: The repository 'http://httpredir.debian.org/debian buster-backports InRelease' is not 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.

When i try to add the Keys this comes:

gpg: keyserver receive failed: Server indicated a failure

[ryecoaaron]

Is this an RPi?

[PaulTimmermann]

yes but i solved it was something with an error on my router.

[ypypjay]

@PaulTimmermann could you provide your solution to me,please?I encountered the same problem