Image generation in progress. Try again shortly. (503 service unavailable) I have two exact copies of the same code installed in the same server running a common AMP stack (I am using bitnami). One copy is named as 'dev' and another one is 'prod'.

Only they have their own database &amp; files (which are clones as well).

In dev, Image styles work just fine. I do drush if - it deletes the styles and creates when viewed.

But in prod, drupal throws 503 service unavailable with a Image generation in progress. Try again shortly. content on the first hit (or until the image is generated).

Of-course that comes from image.module line 858, when drupal finds a lock. And somehow setting image_allow_insecure_derivatives to TRUE might solve this issue.

What I don't understand is why its happening! And whats the remedy?

Thanks!
I managed to fix it! 

It was a server configuration issue (PageSpeed (bitnami) to be specific).

I tail -fed the access log and saw 

xxx.my.ip.xxx - - .... "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/32.0.1700.102 Safari/537.36"

xxx.server.ip.xxx - - .... "Serf/1.1.0 mod_pagespeed/1.6.29.2-"


Figured out definitely something is wrong with server (why is it hitting twice!).

Disabled and it worked fine

# Include conf/pagespeed.conf
# Include conf/pagespeed_libraries.conf


This issue was not happening in the dev site maybe because I have apache basic http authentication enabled (hence pagespeed was not caching it, just guessing).