Ubuntu: fixing apt NO_PUBKEY errors by converting deprecated keyring to signed-by attribute
If apt update throws warnings about invalid signature verification and NO_PUBKEY, you may need to migrate from using the deprecated system keyring to using a ‘signed-by’ attribute in your apt repo definition file. Here are examples of errors you might see when doing an ‘apt update’. W: An error occurred during the signature verification. The … Ubuntu: fixing apt NO_PUBKEY errors by converting deprecated keyring to signed-by attribute