## The problem
Issue grafana/grafana#61524 (closed, 34 comments): **What happened**: After following the blog about update regarding CircleCI security updates we are seeing GPG error for verifying apt.grafana.com
Err:4 mount the host path https at container path //apt.grafana.com stable InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9E439B102CF3C0C6
Reading package lists... Done
W: GPG error: mount the host path https at container path //apt.grafana.com stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9E439B102CF3C0C6
E: The repository 'https://apt.grafana.com stable InRelease' is not...
## What fixed it
A GPG NO_PUBKEY error on apt.grafana.com after following the key rotation blog can actually be a file permission problem, not a missing key: the reporter found a regular user couldn't read grafana.gpg inside /etc/apt/keyrings even though the directory looked readable. Fix: rename the keyrings directory, recreate it, and move grafana.gpg back in, then apt update again.