FaceTime for Mac not working on my husband's IMac mid-2007 after upgrade to El Capitan but it works fine on my iMac mid-2011 with El Capitan.
MY husband is having the exact same problem as several people have described here. We both upgraded our Macs to El Capitan on the same day. Facetime for Mac works fine on my Mac. It no longer works on his. When he tries to initiate a call, as soon as it begins to connect Facetime quits unexpectedly.,and generates a multi-page error report. Same thing happens when he tries to receive a call. We spent the evening on the phone with Apple support and no success resolving it (SMC reset, PRAM reset, test account - nothing helped). The Apple senior advisor's recommendation was to reinstall Mac OSX from the Recovery Drive which we will try tomorrow morning. If that does not fix it, the next suggested step is to do an erase and reinstall. No explanation as to what is causing the problem except that it appears to be a corrupted FaceTime installation, or a corrupted upgrade, not sure which. The El Capitan upgrade seemed to install fine on both of our Macs; however, we will try Lincoln Davis's suggestions on signing out of FaceTime on all devices first then signing back in to see if that helps. Neither of our Macs have any anti-malware or anti-virus SW installed; however, the Apple advisor did find a couple of very old MacKeeper plist files in the Launch Daemon folder under Application Support in Library. The Apple advisor had us trash them, but this still did not fix it. My husband's Mac has not had the MacKeeper SW on his Mac for over four years, and his Mac has been upgraded to various versions of OS X before El Capitan without a FaceTime problem. This problem seems to be specific to El Capitan and FaceTime. That's all we know for now. I will post more when I know more.
iMac, OS X El Capitan (10.11), 2.4 GHz Intel Core 2 Duo mid-2007