Apigee has become aware that certain AddTrust/USERTrust intermediate and root CA certificates have expired today. If your keystore makes use of these certificate, you will need to create a new keystore and update your references to include the new intermediate root certificates. If you do not use these CA certs in your keystores, you need take no action as this will not affect you. Customers must fix these errors, as these are errors in customer manager certificates, not Apigee controlled certificates.
This affects the following certs
Intermediate: USERTrust RSA Certification Authority
Root: AddTrust External CA Root
Symptoms: 503 ServiceUnavailableException and/or SSL handshake errors
Resolution: Please follow the instructions at this link -- https://docs.apigee.com/api-platform/system-administration/update-tls-certificate-cloud#update-a-tls-certificate-in-a-keystore