WHMCS Back-End Client Domains Tab 500 Internal Server Error

[ZMACKs]

Hello guys, I have a strange problem in the domains tab of a client in WHMCS back-end:
(Clients >> View/Search Clients >> ClientName >> Domains)

When I click on this tab, it takes too much time to execute, about 20 or 30 seconds and then ends up with 500 internal server error. The whole script works fine with no errors including registrations, support tickets, processing payments and everything. I'm wondering why does this page specifically encounter this problem!

This is the apache error log:

[Thu Jul 31 11:15:48.416292 2014] [core:error] [pid 4779:tid 140271276754688] [client 102.82.20.131:51873] Script timed out before returning headers: clientsdomains.php, referer: https://whmcs.domain.com/admin/clientsinvoices.php?userid=29

I have total control on the server and I increased the php limits to 256M and max_execution_time to 900, I increased everything but still doesn't work. WHMCS staff didn't help me much, they said that this is a server issue and out of their support scope.

Does anyone had this problem before? Any suggestions guys? Your replies would be greatly appreciated. Thank you

 

[cPanelMichael]

Hello

Please ensure you try posting to the WHMCS forums:

WHMCS Forums

There are dedicated WHMCS staff members available to help with threads there.

Thank you.