Installing Grafana extension on Plesk server with Ubuntu fails: The following signatures were invalid: <pub_key> (untrusted public key algorithm: dsa1024)

Taras Ermoshin

Updated February 26, 2026 04:18

Plesk for Linux kb: technical

Applicable to:

Plesk for Linux

Symptoms

On a Plesk server with Ubuntu OS, installing Grafana extension fails:
On Plesk servers with other Ubuntu/Debian versions, checking for package updates may fail:

CONFIG_TEXT: Err:11 https://autoinstall.plesk.com/grafana/deb stable InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E9299045CE550E57
.....
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://autoinstall.plesk.com/grafana/deb stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E9299045CE550E57
W: Failed to fetch https://autoinstall.plesk.com/grafana/deb/dists/stable/InRelease The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E9299045CE550E57
W: Some index files failed to download. They have been ignored, or old ones used instead.

Cause

Grafana extension repository was signed with GPG key with weak algorithm.

Resolution

GPG key of the Grafana repository was updated, and Grafana extension was updated in order to apply the repository changes, so the issue should be resolved if the Grafana extension is up-to-date.

If the issue still occurs, update the Grafana extension to the latest version.

In case the above is not helpful, check whether the Grafana extension was updated properly - upon updating, it should fully replace the repository with the correct key.

If absolulutely necessary, execute the following command to update the key:

# wget -q -O - https://autoinstall.plesk.com/grafana/deb/gpg.key | gpg --dearmor > /etc/apt/keyrings/plesk-ext-grafana.gpg