White empty screen on Save and viewing Status report page

One of my clients has a very simple website. Using Articles, Gallery, Views module and some utility modules. The website was running for a year on 7.14 and recently I upgraded it to 7.24. Upgrade from 7.14 to 7.24 went almost fine and website and theme was working fine.

Some pages I was getting a white empty screen like on Admin >> Status report. However I did not care that that , I thought it must be an issue with my browser cache.

Later Client called me that he is not able to edit or save any content , neither they are able to edit blocks. The moment they hit Save button, they would get white empty screen and they are not sure what is going on.

I read WSOD article on drupal.org and tried to

1. Increase the memory limit to 128M in settings.php and also in .htaccess file but no luck
2. I refreshed all drupal files by untarring the drupal tar file , but no luck'
3. I Flushed all cache and checked again, but no luck
4. Most people had reported on drupal and other websites that space at end of template.php was cause of their WSOD, in my case there was a new line character I deleted that but still no luck
5. Added error reporting code to my index.php but did not get any errors.

Was breaking my head for almost 90 mins and couldnt find a solution.

Finally for no reason I checked which were outdated modules and out of all the ones I only updated Token module and ran the update.php script. To my surprise the WSOD disappeared and we are able to save the block pages and view status reports.

I sincerely hope that WSOD issue is fixed in Drupal 8 or there is a better way to debug this issue.