Q: Webex can no longer connect to meetings after upgrading to Yosemite.

Well, I didn't have this issue until I updated to a new MacBook Pro.  The earlier MacBookPro was running WebEx without issue. I wondered if it was due to a poor install of WebEx.  I went through the tedious manual removal of WebEx and downloaded the latest version of WebEx.  Same result.  Just indicates I'm no longer in the meeting and it will reconnect automatically, but never does.  I tried Safari and FireFox (not a fan of Chrome).

At home, if I switch form Auto Proxy config URL to No proxy, I can get WebEx to work.  Of course that doesn't help me when I'm back in the office have have to use a Proxy server.  Same settings work fine in Windows, which I have installed via Parallels.  I have to use Windows to run WebEx meetings regardless if I'm home or in the office, with not proxy changes required.  Not the work around I had hoped for.  So I cannot determine if the problem is with the Proxy or with OS 10.10.  I can't help blame OS 10.10, as the same proxy settings work fine on my Mac via Windows.  Will a solution automatically happen for me?  I can only hope.

I had the same issue and I fixed it by disabling "Auto Proxy Discovery" and "Automatic Proxy Configuration" in the Network -> Proxies tab.

Thanks. This helped me. I was instantly able to get connected to webex. normally it would hang at 98%..

I used to have the same issue with El Captain 10.11.6 connecting to webex will hang at 98%. This reply helped and was able to connect to webex.... Thanks.