"proxy: ap_get_scoreboard_lb failed"

[Moses Moore]

cPanel/WHM did it's auto-upgrade thing a few days ago (now at cPanel/WHM 64.0 build 15) and every day now I'm seeing a few hundred of these in the Apache error logs every day:

[Mon Apr 24 07:56:19 2017] [error] proxy: ap_get_scoreboard_lb(21) failed in child 5422 for worker proxy:reverse

[Mon Apr 24 07:56:19 2017] [error] proxy: ap_get_scoreboard_lb(18) failed in child 5422 for worker http://127.0.0.1:2082

[Mon Apr 24 07:56:19 2017] [error] proxy: ap_get_scoreboard_lb(19) failed in child 5422 for worker http://127.0.0.1:2077

[Mon Apr 24 07:56:19 2017] [error] proxy: ap_get_scoreboard_lb(20) failed in child 5422 for worker http://127.0.0.1:2095

[Mon Apr 24 07:56:19 2017] [error] proxy: ap_get_scoreboard_lb(17) failed in child 5422 for worker http://127.0.0.1:2095

[Mon Apr 24 07:58:05 2017] [error] proxy: ap_get_scoreboard_lb(21) failed in child 5753 for worker proxy:reverse

[Mon Apr 24 07:58:05 2017] [error] proxy: ap_get_scoreboard_lb(18) failed in child 5753 for worker http://127.0.0.1:2082

[Mon Apr 24 07:58:05 2017] [error] proxy: ap_get_scoreboard_lb(19) failed in child 5753 for worker http://127.0.0.1:2077

[Mon Apr 24 07:58:05 2017] [error] proxy: ap_get_scoreboard_lb(20) failed in child 5753 for worker http://127.0.0.1:2095

[Mon Apr 24 07:58:05 2017] [error] proxy: ap_get_scoreboard_lb(17) failed in child 5753 for worker http://127.0.0.1:2095

[Mon Apr 24 07:58:07 2017] [error] proxy: ap_get_scoreboard_lb(21) failed in child 5773 for worker proxy:reverse

[Mon Apr 24 07:58:07 2017] [error] proxy: ap_get_scoreboard_lb(18) failed in child 5773 for worker http://127.0.0.1:2082

[Mon Apr 24 07:58:07 2017] [error] proxy: ap_get_scoreboard_lb(19) failed in child 5773 for worker http://127.0.0.1:2077

[Mon Apr 24 07:58:07 2017] [error] proxy: ap_get_scoreboard_lb(20) failed in child 5773 for worker http://127.0.0.1:2095

[Mon Apr 24 07:58:07 2017] [error] proxy: ap_get_scoreboard_lb(17) failed in child 5773 for worker http://127.0.0.1:2095​

This just looks like something that cPanel/WHM is using internally to talk to itself (ports 2082 and 2095 are cpservd, but nothing's listening on port 2077). But I'm awfully nervous because this could also be some foreign code trying to insinuate itself into cPanel and failing repeatedly.

I already checked stackexchange and mailing lists, the answer I get is "you configured ProxyPass in apache wrong," but I didn't touch apache config, only thing that could've changed it would be WHM auto-updating itself.

 

[cPanelMichael]

Hello,

Could you verify if you are using any third-party applications such as Nginx on this system?

Thank you.

 

[Moses Moore]

I'm not using other http daemons, if that's what you mean.
I added 'atd' to the machine (like crond for one-off jobs, normal Unix/BSD stuff) but the at queues have been empty for weeks so I don't think that's it.

 

[cPanelMichael]

Hello,

Could you open a support ticket using the link in my signature so we can take a closer look at the affected system? You can post the ticket number here so we can update this thread with the outcome.

Thank you.

 

[Moses Moore]

Can't open a ticket, your ticketing website says I have to go to my hosting company and ask them first.
There's no way they'll know something this esoteric, but bureaucracy demands compliance.

 

[GOT]

We have servers getting this error and leading to an apache segfault condition. We are running Unixy's Varnish plugin.

Thoughts?

 

[GOT]

Looks like recompiling apache resolved this.

 

[cPanelMichael]

Hello,

I found a similar report in a recent support ticket on a system running EasyApache 3. The issue related to a bug with mod_proxy_balancer on Apache 2.2:

58267 – " Error ap_proxy_set_scoreboard_lb(xxx) failed in child xxx for worker xxx " flooding in error log

The resolution to this Apache bug is included in the latest version of Apache 2.2 offered in EasyApache 3, and thus running a new EasyApache build corrected the problem.

Thank you.