BUG #18268: Failed to validate GPG signature for pgdg-redhat-repo-42.0-38PGDG.noarch

The following bug has been logged on the website:

Bug reference:      18268
Logged by:          Adam Smith
Email address:      adam.smith@matillion.com
PostgreSQL version: 13.13
Operating system:   AL2 and Centos8
Description:

We are getting failures when installing Postgres 13 with GPG enabled. 

We think something has happened with the keys on your side. 

warning:
/var/cache/yum/x86_64/2/pgdg13/packages/postgresql13-libs-13.13-1PGDG.rhel7.x86_64.rpm:
Header V4 RSA/SHA1 Signature, key ID 73e3b907: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-PGDG-13

The GPG keys listed for the "PostgreSQL 13 - Amazon Linux 2 - x86_64"
repository are already installed but they are not correct for this
package.
Check that the correct key URLs are configured for this repository.

We downloaded the key from:
https://download.postgresql.org/pub/repos/yum/RPM-GPG-KEY-PGDG-13

I think you've had this issue before. 

Kind regards
Adam