JSON error in uploading product images

[fx3]

When I try to upload most images (some small ones have worked fine) I get a red triangle without any error and it seems like the image is there, but shows a ? instead.

 

Firebug reports:

500 Internal Server Error

  4.14s

 

in the console and when I enable debugging I get a JSON error where previously there was just a red box next to the alert triangle.

 

The PHP upload setting is 32M and the images ~3MB. I'm using EDA theme which has an imagemanager override but even when disabled the problem persists.

 

Can't seem to figure out what is causing it.

 

Server software version Apache mod_fcgid/2.3.10-dev

PHP version 5.4.31

Memory limit 64M

Max execution time 120

PrestaShop version 1.6.0.9

Edited October 16, 2014 by fx3 (see edit history)

[NemoPS]

Is error reporting enabled? What is the json response you get? You should inspect the XHR call in the network tab to see exactly what you get, there might be some ad coming from the server (it happens at times)