What is the most likely reason for certificate errors occurring on multiple servers after an SSL certificate has been revoked?

The most likely reason for certificate errors occurring on multiple servers after an SSL certificate has been revoked is that the servers used a wildcard certificate. Wildcard certificates allow for securing multiple subdomains of a domain under a single certificate, making them a convenient option. However, if a wildcard certificate is revoked, all subdomains and servers that rely on that certificate are affected simultaneously. This would lead to widespread certificate errors across multiple servers because they are all dependent on the same compromised certificate.

In many scenarios, revoking a certificate impacts not only the primary domain but all associated subdomains as well, which aligns with the situation described in the question. Thus, the use of a wildcard certificate directly correlates to the occurrence of certificate errors across multiple servers after revocation.