I am getting randomly the 502 bad gateway on my site. When I check the hhvm logs I am getting this error:

Fatal error: Class undefined: Mage_Facebookfree_Helper_Active in /mypath/Mage.php on line 547

The Belvg/Facebookfree module is disabled from admin panel and from modules/Belvg_Facebookfree.xml


Also I commented all of the code when the helper is called from the design folder. What should I try more ? and why I am getting this error randomly ? thx

UPDATE After I removed the line from core_config_data I got again 502 and in the logs i got this message:

SlowTimer [1308ms] at runtime/ext_mysql: slow query: SELECT COUNT(*) AS `count` FROM `mydb`.`catalog_product_entity_datetime` WHERE (CONVERT(`value_id` USING utf8) LIKE '%advanced/modules_disable_output%' OR CONVERT(`entity_type_id` USING utf8) LIKE '%advanced/modules_disable_output%' OR CONVERT(`attribute_id` USING utf8) LIKE '%advanced/modules_disable_output%' OR CONVERT(`store_id` USING utf8) LIKE '%advanced/modules_disable_output%' OR CONVERT(`entity_id` USING utf8) LIKE '%advanced/modules_disable_output%' OR CONVERT(`value` USING utf8) LIKE '%advanced/modules_disable_output%')

this is one of the many tables. There is multiple slow timer errors

  • Did you clear the configuration cache ?
    – hellimac
    Dec 28, 2015 at 7:29
  • I cleared all of the cache from var/cache Dec 28, 2015 at 7:33
  • I can't understand that query, there is no relation at all between catalog_product_entity_datetime and advanced/modules_disable_output Dec 28, 2015 at 9:02
  • I know, but this is what my hhvm logs showed me after I removed from core_config_data the line with the path advanced/modules_disable_output/Belvg_Facebookfree and with the value 1. Before I got the fatal error message Dec 28, 2015 at 9:04
  • That query It's simply ridiculous, there is something really wrong there ... maybe related to some cache or code compilation try to remove all caches and restart HHVM. BTW try to test your code in a php 5.x environment if you can to avoid any HHVM incompatibility issue. Dec 28, 2015 at 9:10

2 Answers 2


Please try:

  1. Clean all HHVM compilation cache (i don't know how it works exactly but as far as I know hhvm magic is based on compilation)

  2. If still happens, look for any layout xml(specially local.xml on your theme)/*.phtml/config.xml/attribute using that helper.

  3. if you can, remove the entry with path: advanced/modules_disable_output/[that_module] on core_config_data table.

If problem persist turn developer_mode ON or look at the exception.log to find the complete error stack.

  • I found in the core_config_data this advanced/modules_disable_output/Belvg_FacebookFree and its value 1. should i remove it ? Dec 28, 2015 at 8:05
  • Yes, don't worry you can remove all advanced/modules_disable_output without any problem, these values doesn't exist until you save this section for a first time. It's common to find entry for removed modules there. However i think that the problem lies in a layout or template file... i guess Dec 28, 2015 at 8:12
  • I did the third one. I did a grep after facebookfree/active. I found a lot of entries. I commented it all of them and renamed the xml file of that module. Also I found no entries in the local.xml or other xml file. How do i do the first one ? Dec 28, 2015 at 8:19
  • I have no idea about how to force re-compilation in HHVM :(. Try to turn developer mode on maybe we could get a best error trace. Dec 28, 2015 at 8:25
  • I updated my post can you check it? thx Dec 28, 2015 at 8:49

I was experiencing 502 Bad Gateway errors as well and it turns out that my disk quota had been reached. I confirmed with my host and started removing old backups. My site instantly came back.

Things to try:

  • Try removing any unwanted backups
  • Clear out the session logs
  • Remove anything that you know that you don't need (old databases)
  • Increase your Disk Space Quota with you host

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