How the problem manifests
When working with APT (e.g. apt update), an error about an invalid key is displayed:
EXPKEYSIG 70E18E2B
Cause
The GPG key for the repository has expired.
👉 As a result, the system refuses to verify packages.
Solution
Update the key using the following command:
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 70E18E2B
Note
The issue may occur after an extended period without updates.
After renewing the key, run
apt updateagain.