XF 1.4 child pid exit signal Segmentation fault (11)

[Chad]

Was testing an html email send to admin group and kept getting a page not found on send test email.

My server logs show:

[core:notice] [pid 31130] AH00052: child pid 9822 exit signal Segmentation fault (11)

I'm running my own dedicated server with the following:

Apache 2.4
PHP 5.4
MySQL 5.6
No cache is running yet.

Not sure why this is happening.

 

[Chad]

Nevermind, I think there was a conflict of cache modules. Sorry.

 

[Alpha1]

@Chad I am trying to upgrade my server from Debian 7 to Debian 8 and am running into the exact same error:
child pid exit signal Segmentation fault (11)

Do you remember what cache modules had a conflict or any other information?
I have no clue where to look, so any help would be awesome.