Error code

Firefox SEC_ERROR_REUSED_ISSUER_AND_SERIAL

FIREFOXSEC_ERROR_REUSED_ISSUER_AND_SERIAL
Browser Error Code· An error code shown in a web browser when a page fails to load.

What it means

A different certificate with the same issuer and serial number was already seen.

How to fix it

  1. This is a CA error.
  2. contact the site owner to get a freshly issued certificate with a unique serial number.

Not affiliated with Firefox. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.