The CA/Browser Forum baseline requirements specify 15 reasons why a key may need to be revoked. You can read all 15 here, but they can be summarized as: • A security incident occurs (or is believed to have occurred) on your server (or any other computer where the private key is used or stored). • A staff member with access to your private key leaves. • The private key file is deleted, destroyed or lost. • There was an error in generating the key pair. A security breach is a good time to update your security practices, and to report your key compromised. Again, it’s better to err on the side of caution when it comes to your certificate safety. If your key has been compromised or you suspect it has been, submit a revocation request to your CA immediately.