Earlier today I noticed that this subdomain was producing 500 internal server error. I tracked it down to the fact that I’d updated PHP to 7.1.2 while trying to debug a problem where PHP_SAPI was not constant. I hadn’t noticed that Jetpack 4.4.2 causes segmentation errors with this version of PHP.

The version of PHP is 7.1 until Jetpack has been updated to 4.7