The Public Key size of the Certificate with Subject should be at least 2048

Installation/ upgrade failures

Validate the PUBLIC KEY of the Certificate in the DETAILS section that is being used during the Installation or the upgrade. With 20.4 onwards it is mandatory to have a Key with at least 2048 bits. If the domain certificate is less than 2048, temporarily create a Self-Signed certificate and proceed with install/upgrade and request customer to procure the required certificate.