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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

One thought on “Secure Connection Failed CUCM/CUC/UCCX”

  1. Claudio says:

    Hello Friends,
    The problem of that procedure is you perform at your own risk.
    If you really want to do a right support you should do an upgrade to the next version, in my case I have the CUCM version and I should go to CUCM version.

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Electrical Engineer CCNA Collaboration CCNA Voice CCNA R&S. I'm Electrical Engineer and I work like Support Engineer for a Telephony Service Provider Company. Before that I had position like Pre-Sale Engineer about small and medium multivendor telephony solutions. I have 5 years of experience working in Telephony Multivendor Projects. I am also 3 years of experience working in Support and implementation about Cisco Collaboration platforms: UCS server, UCM, Cisco Unity, Presence Server, Jabber, Gateway. Support Community is most useful in finding design, implementation and support tricks and shortcuts that greatly help me in my daily activities. If you need to contact me, please you can writte me.


CCNA Routing and Switching
Am a technology enthusiast. I work in network support providing support with implementation, maintaining and precisely troubleshooting the infra.
Realm of collaboration makes me want to learn and face new challenges more and more.