Wordpress Fatal error: Uncaught Error: Call to undefined function mysql_connect() in /wp-includes/wp-db.php:1570

user_6517924 0
Viewed 45657

I am in big trouble. I installed a nulled version of woocommerce cart based shipping plugin and i found it not relevant according to my requiremnet and deleted that plugin from plugins area. After deleting that plugin my site went down. Its continuously showing me Fatal error:

Fatal error: Uncaught Error: Call to undefined function mysql_connect() in /home/dev/public_html/new/wp-includes/wp-db.php:1570
Stack trace:
#0 /home/dev/public_html/new/wp-includes/wp-db.php(658): wpdb->db_connect()
#1 /home/dev/public_html/new/wp-includes/load.php(404): wpdb->__construct('dev_test', 'password', 'dev_test_ne...', 'localhost')
#2 /home/dev/public_html/new/wp-settings.php(107): require_wp_db()
#3 /home/dev/public_html/new/wp-config.php(82): require_once('/home/dev/p...')
#4 /home/dev/public_html/new/wp-load.php(37): require_once('/home/dev/p...')
#5 /home/dev/public_html/new/wp-blog-header.php(13): require_once('/home/dev/p...')
#6 /home/dev/public_html/new/index.php(17): require('/home/dev/p...')
#7 {main} thrown in /home/dev/public_html/new/wp-includes/wp-db.php on line 1570

I tried replacing all core files excluding wp-config.php and wp-content folder. Still I am getting the same error.

Also, i tried renameing plugins folder but the error is there.

Can you guys suggest me how i can get my site back.

fatal-error wordpress mysql php
9 Answers

I encountered this problem upgrading from PHP 5 to PHP 7 (on Windows). The problem was mysqli PHP extension was not enabled. If mysqli is not available Wordpress 5+ detects this and will instead attempt to connect to the database with deprecated mysql_connect() calls. This leads to a very misleading error message about mysql_connect() function not being available (since we don't want this function).

In php.ini make sure extension_dir is set (use full directory name) and mysqli extension is enabled

extension_dir = "C:\php-7.3.10\ext"
...
extension=mysqli

To double check what extensions are active you can run the following code

<pre>
<?php print_r(get_loaded_extensions()); ?>
</pre>
user_2117640

It happens for me when I switch from 5.6 php to 7.0.

Just enable "mysqli" in your select php version if you use cPanel.

user_42100530

Just registered to give a big thank you for the solution of enabling mysqli. I have been struggling to get WordPress running on a Synology for the past 3.5 hours and this finally fixed my dreaded "The site is experiencing technical difficulties."

For any other Synology users ending up in this topic after trying to find a solution, to fix this on Synology, you need to...

  • Go to Web Station
  • Select PHP Settings
  • Double-click the PHP profile you are using (or click once and choose [Edit])
  • Select General Settings and scroll to the extensions list
  • Find mysqli and enable by placing a checkmark
  • Push the [OK] button (no restart required)
user_132275990
user_95891800

Just had a similar problem with a cpanel multiphp instance. Tried just about everything but while cpanel/whm was saying all was fine, the site would crash when 7.x was activated.

In the end, it was the .htaccess file. We renamed and let Cpanel regenerate and all is good.

Hope this helps someone out there as it took some time to resolve here.

user_122891310

i had same kind of issue for my web hosting client at magicworkshost , i have updated php version from 5.6 to 7.3 and issue resolved successfully.

Thanks

user_152644880 
sudo apt-get install php7.4-mysql
sudo service apache2 restart
user_2127020
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