Question

Wordpress Site on digital ocean frequently returns 504 Bad Gateway

Posted February 5, 2021 235 views
NginxPHPWordPressUbuntu 16.04

I had a similar issue in the past with a Laravel application and I was able to fix it by reducing the workload on pulling info from the DB.

But this time is a WordPress application hosted on Ubuntu 20.04 (LTS) x64 1 vCPUs
1GB / 25GB Disk
I get this 504 Bad Gateway error 3-4 times daily and each time this error occurs, the site is down for about 5-10 minutes.

Here is the output from free -m

              total        used        free      shared  buff/cache   available
Mem:            981         741          69          80         169          40
Swap:             0           0           0

And the output I get from mpstat

Linux 5.4.0-51-generic (ubuntu-s-1vcpu-1gb-nyc1-01)     02/05/21        _x86_64_        (1 CPU)

21:59:40     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
21:59:40     all    3.59    0.02    1.17    0.63    0.00    0.06    0.02    0.00    0.00   94.52

And lastly the output from iostat 1

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.00    0.00    0.00    0.00    0.00  100.00

Device             tps    kB_read/s    kB_wrtn/s    kB_dscd/s    kB_read    kB_wrtn    kB_dscd
loop0             0.00         0.00         0.00         0.00          0          0          0
loop1             0.00         0.00         0.00         0.00          0          0          0
loop2             0.00         0.00         0.00         0.00          0          0          0
loop3             0.00         0.00         0.00         0.00          0          0          0
loop4             0.00         0.00         0.00         0.00          0          0          0
loop5             0.00         0.00         0.00         0.00          0          0          0
loop6             0.00         0.00         0.00         0.00          0          0          0
loop7             0.00         0.00         0.00         0.00          0          0          0
vda               1.00         0.00         4.00         0.00          0          4          0

Thanks

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1 answer

Hello, @supportAnemone

The issue is most likely related with the PHP-FPM service. The first thing I’d recommend, before we get started with the configuration, would be to tail the logs.

tail -n 50 /var/log/nginx/error.log

Also, let’s take a look at the PHP-FPM log, which should be in /var/log as well.

tail -n 50 /var/log/php$-fpm.log

Keep in mind that you need to select the fpm log for the PHP version in use.

You can also share the content of the php-fpm pool config file so we can check if we need to increase any of the settings like the pm.max_children because the issue is most probably related with the fact that the server have reached the pm.max_children limit.

Regards,
Alex