Error establishing a database connection

Posted April 27, 2016 4.3k views

Today I have started to see in my website this message “Error establishing a database connection”, so I was investigating and I saw this article related and I have tried to implement it but its not working for me I still getting the same issue and I have no clue why.

Below is what I have implemented from the article:

For Apache on Ubuntu 14.04, edit the configuration file with the following command:

sudo nano /etc/apache2/sites-available/000-default.conf
Add the highlighted lines below between the <VirtualHost> tags.

Apache VirtualHost Config

<files xmlrpc.php>
order allow,deny
deny from all
Save and close this file when you are finished.

Restart the web server to enable the changes:

sudo service apache2 restart

What is weird is when I restart the droplet the website works for a couple of seconds so.. I cant figure out how to fix it.

Droplet details:
512 MB Memory / 20 GB Disk / LON1 - Ubuntu WordPress on 14.04

These answers are provided by our Community. If you find them useful, show some love by clicking the heart. If you run into issues leave a comment, or add your own answer to help others.

Submit an Answer
4 answers

Problem solve with this code..

sudo start mysql

have a nice day !

Run the following after you start seeing that, and look at the output:

free -m

My bet is it looks something like this:

             total       used       free     shared    buffers     cached
Mem:          512       512        0         256        256       0
-/+ buffers/cache:       256       0
Swap:            0          0          0

If Mem and buffers/cache both show 0 free, you’re overutilizing the server, and need to move to at least a 1GB server.

  • Hey I was working on it and I found an error here -> /var/log/mysql/error.log you can see the error here, so basically I have added a swap following this tutorial and now it’s working but some times takes to much time to open the website.. I only have a static website so I don’t know why is so slow.
    Any idea? Thanks!!

    by Justin Ellingwood
    Swap space can be used as an "overflow" area for your system when you run out of RAM. The operating system can store data that would normally be kept in RAM on the hard drive in a specially formatted file. In this guide, we'll demonstrate how to create and use one of these files in Ubuntu 14.04.
    • Put simply, your server isn’t big enough to run your site.

      I’m going to write this up so I can reference this post every time something like this happens, so don’t think I’m picking on you.

      Picking the smallest server to save money won’t actually be the best route. If you are running more than one service/daemon (Apache2/MySQL, for example), you need to think in these terms:

      512MB MINIMUM for MySQL – this is at a minimum, and that may not be enough
      256MB MINIMUM for Apache2 for each 100 visitors in a 1-minute average
      50MB MINIMUM for PHP for each 100 visitors in a 1-minute average

      128MB MINIMUM for NGINX for each 100 visitors in a 1-minute average
      256MB MINIMUM for MariaDB – this is at a minimum, and that may not be enough
      30MB MINIMUM for PHP-FPM for each 100 visitors in a 1-minute average
      14MB MINIMUM for HHVM for each 100 visitors in a 1-minute average

      All these numbers are at a minimum.

      Take what I have as the minimum, and add 60% to that, then you have a good starting point as to what you will need, so for example:

      Apache2/MySQL/PHP, and you service 500 people in a minute:

      (512MB + (256MB* 4 = 1GB) + 450MB) * 1.60 = 3177.6MB. In this case, you would go with a 4GB server. If you have to pick to go up or down, always go up in size.

      Remember: these numbers aren’t magical. They won’t fix every scenario. If, for example, you have 100 plugins on a WordPress site, it may take 4GB to service 1 person a minute.

      These are just basic rules that are good to get a baseline on the bare minimum of what you need.

You might want to verify that you’ve properly blocked requests to xmlrpc.php. You can do that with the following command:

curl -XPOST http://YOUR_DOMAIN/xmlrpc.php

if you see this, you have not blocked requests to xmlrpc.php:

<?xml version="1.0" encoding="UTF-8"?>
          <value><string>parse error. not well formed</string></value>

Hello all,

This crash is most likely due to your system running out of memory. I’d suggest that you add a swap file to give yourself a bit more of a buffer. Check out this tutorial:

How To Add Swap on Ubuntu 18.04

What you can also do is to use the MySQLTuner script.

The MySQLTuner is a script written in Perl and allows you to quickly test your MySQL configuration and it gives you suggestions for adjustments to increase performance and stability.

According to the official GitHub page, it supports 300 indicators for MySQL/MariaDB/Percona Server in this last version.

To run the script you could do the following:

  • SSH to your Droplet
  • Download the script:
wget -O
  • Then execute it:

The script would run multiple checks against your MySQL instance, all checks done by MySQLTuner are documented here.

Also as stated in the official documentation, it is still extremely important for you to fully understand each change you make to a MySQL database server. If you don’t understand portions of the script’s output, or if you don’t understand the recommendations, you should consult a knowledgeable DBA or system administrator that you trust.

As a good practice make sure to always test your changes on staging environments before implementing them on your production database.

On the same note, if you want to have worry-free MySQL hosting and focus on your application, I would recommend trying out the DigitalOcean Managed Databases:


Hope that this helps!