I recently ran into this error after updating and rebooting a server “sec_error_ocsp_try_server_later” this happened with Firefox and up until the update there had been no issue. The weirdest part was that nothing that could impact either Apache or the SSL had been updated. After re-installing the actual SSL and seeing the same error I figured why not try an Apache restart.
Guess what? Voila problem solved, and it still remains a mystery as to why this error appeared and than disappeared after a restart.