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Secure Connection Failed CUCM/CUC/UCCX

Secure Connection Failed CUCM/CUC/UCCX

If you are using Firefox you may encounter an error “Secure Connection Failed”, An error occurred during a connection to X.X.X.X:8443. SSL received a weak ephemeral Diffie-Hellman key in Server Key Exchange handshake message. (Error code: ssl_error_weak_server_ephemeral_dh_key) when you try accessing CUCM, CUC or UCCX.

Either change your browser from Firefox to Chrome or Internet Explorer else make some changes on Firefox settings to fix this issue.


  • Launch FireFox, type “about:config” in the URL field and hit enter.
  • Accept “This might void your warranty!” warning
  • In the search field at the top, type “security.ssl3.dhe_rsa_aes
  • Double click on each result (128 and 256) to toggle the Value to “”
Again try accessing CUCM/CUC/UCCX and this should fix the issue.

Published by Team UC Collabing

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