After upgrading to virtuemart 2.6.12 from 2.0.22a i followed the advise to upgrade virtuemart aio too so after completing the uploading and installation throuth joomla installer all i get is a white page without the component being really upgraded. I am not sure if this or the upgrade of virtuemart itself caused me also a white page on every product page too.
See http://forum.virtuemart.net/index.php?topic=117042.0
So i did what you proposed and this is the error i am getting on product pages, i don't know about virtuemart aio installation what is causing white page, might be the same.
Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 122880 bytes) in /home/********/public_html/plugins/content/pagenavigation/pagenavigation.php on line 126
and in my error log i have several errors after the upgrade of virtuemart and virtuemart aio most of them look like this:
[27-Oct-2014 15:30:49 Europe/London] PHP Warning: Invalid argument supplied for foreach() in /home/*******/public_html/templates/gk_esport/html/com_content/category/blog_item.php on line 22
[27-Oct-2014 15:32:20 Europe/London] PHP Warning: Invalid argument supplied for foreach() in /home/*******/public_html/templates/gk_esport/html/com_content/article/default.php on line 17
[27-Oct-2014 16:18:08 Europe/London] PHP Notice: Undefined variable: itemid in /home/*******/public_html/modules/mod_news_pro_gk4/tmpl/layout.parts.php on line 1265
[27-Oct-2014 16:18:08 Europe/London] PHP Notice: Undefined variable: news_text in /home/*******/public_html/modules/mod_news_pro_gk4/tmpl/layout.parts.php on line 1269
[27-Oct-2014 16:18:08 Europe/London] PHP Notice: Undefined property: stdClass::$_triesValidateCoupon in /home/*******/public_html/components/com_virtuemart/helpers/cart.php on line 123
OK i changed max memory to 64M and everything worked.
Thank you
Would recommend at least 128MB if possible - we run all our VM sites on 256MB