upstream timed out (110: Connection timed out) while reading response header from upstream

Posted April 2, 2020 26.3k views

Since a while I’m experiencing 501 timeouts on my DO hosted WP website.

I checked /var/log/nginx/error.log and I’ve gotten about two errors per minute (they stopped all of the sudden and my website is online again since).

The logs contain a bunch of lines which boil down to these two:

connect() to unix:/var/run/php/php7.2-fpm.sock failed (11: Resource temporarily unavailable) while connecting to upstream,client: [REDACTED], server: [REDACTED].com, request: "POST /xmlrpc.php HTTP/1.0", upstream: "fastcgi://unix:/var/run/php/php7.2-fpm.sock:", host: "[REDACTED]"

upstream timed out (110: Connection timed out) while reading response header from upstream, client: [REDACTED], server: [REDACTED].com, request: "POST /wp-cron.php?doing_wp_cron=1585826903.9321999549865722656250 HTTP/1.1", upstream: "fastcgi://unix:/var/run/php/php7.2-fpm.sock", host: "[REDACTED].com", referrer: "https://[REDACTED].com/wp-cron.php?doing_wp_cron=1585826903.9321999549865722656250"

Any suggestions on how track down what is going on?

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1 answer

Hi there @angieCoral,

It looks like that your PHP FPM service is crashing, this is why you are seeing these errors in your Nginx error log.

I could suggest checking your PHP FPM error log for more information on why the service is crashing. The log is usually stored at /var/log/fpm-php.www.log though the location might be different depending on your configuration.

A possible issue here could be that PHP is using too much RAM and the PHP FPM process gets killed. If this is the case I would recommend the following:

  • Make sure that there is enough RAM on the server, to check that you could use the top, htop or free -m commands

  • Make sure that the PHP memory limit is not too high compared to the actual available memory on the Droplet. For example if you have 1GB of RAM available your PHP memory limit should not be more than 64MB otherwise only a few processes could consume all of your memory

  • Optimize your website by installing a good caching plugin, that way you would reduce the overall resource usage on the server

  • Delete any plugins that are not being used. Generally speaking, it is always recommended to try and keep the number of your plugins as low as possible

  • Consider using a CDN like Cloudflare, that way it would offload some of the heavy liftings from your Droplet

As the specific error that you’ve shared is referring to wp-cron.php, another thing that you might want to consider is checking your cron jobs and making sure that there are not running too often or the processes are not too resource consuming. If this is the case, try to reduce the frequency or run the cron jobs during the night when the overall load on the server is low.

And here is also a quick video demo on how to troubleshoot such issues as well:

Hope that this helps!

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