I'm running a WordPress 4.4.2-based membership site on Ubuntu 12.04 LTS with PHP 5.6.20.

After upgrading to 1.9.14 (compiling from source with no errors or warnings), I could no longer log in to my site, using Firefox/Chrome/IE. Trying to login didn't timeout. Instead, fairly quickly, I would get an error message like this in Firefox:

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Secure Connection Failed

The connection to jobmob.co.il was interrupted while the page was loading.

The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
Please contact the website owners to inform them of this problem.

Learn more…
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Tailing the error logs, nothing at all appears when I try to log in.

My WordPress install is Multisite, which means I can have multiple websites running off a single install, and I do. However, only the main website has this login issue with 1.9.14. *I could still log in without a problem in each of the other sites.*

How to troubleshoot this? 1.9.14 has relatively few changes, so I was surprised by this. I've since rolled back to 1.9.13