WHMCS suddenly giving 503 error

[dotcomUNDERGROUND 0]

My WHMCS is suddenly giving 503 Service Unavailable error.  Both the admin and front end.

I have not made any changes to WHMCS or the server. I created a test php file and that loads fine.

Its on a cpanel server running cloudlinux. There is no LVE error for the site.

Any suggestions on how I can troubleshoot the issue?

[Damo 9]

A 503 is resource limits and would be CL. 

There must be something showing as a fault in CL. What are the limits set on this account? 

[dotcomUNDERGROUND 0]

44 minutes ago, Damo said:

A 503 is resource limits and would be CL. 

There must be something showing as a fault in CL. What are the limits set on this account? 

Thank you for your reply.

I have checked the CL history and it does not show any fault. I have also updated cage fs structure and tried applying the "do not limit" setting.

My limits are:

SPEED 600%
VMEM 0
PMEM 10G
IO 10MB/s
IOPS 10240
EP 500
NPROC 1000

Note that I can run a newly created php page with phpinfo() without any issue.

[dotcomUNDERGROUND 0]

I tried switching off php-fpm for the domain and its working fine now.

Any reason for this behavior? Specially when I have not changed any setting or made any upgrade?

[Xhale1 0]

Same issue here. No CloudLinux, just cPanel and LiteSpeed. No server changes and then today I'm getting a 503 error. I think it's related to an update to EasyApache 4?

[nguoiveday 0]

After successfully installing the version whmcs-v7.9.1, you can access the admin page but the external homepage cannot access and report an error: 

503

Service Unavailable

The server is temporarily busy, try again later!

Thanks to you for guidance on how to fix it. Thank you very much!

[Mil1ler 0]

I am also having this issue, does someone have any solution for this? kindly share your views, thanks in advance.

[TorabRamin 0]

I'm facing same issue. 😞 

[GDW 0]

Same problem with sudden 503 error when accessing the login page for WHMCS. Please help!