[Solved] WordPress Upgrade PHP 5.6 to 7.x Fatal error: Uncaught Error: Call to undefined function mysql_connect()

Error reporting when upgrading PHP version 5.6 to 7. X under WordPress (resolved)

Cause of event:

When using WordPress, the theme needs to be upgraded. The PHP version required for viewing the theme is 7.1+

When the website is not backed up, the PHP version is changed to 7.2, which directly leads to the website error

Fatal error: Uncaught Error: Call to undefined function mysql_ connect()

Check many online tutorials, which are MySQL in wp-db.php_Change connect() to mysqli_Connect(), no result

At first, I thought that the database reported an error, checked the database in detail, wrote checkdb.php, locally connected to the database, and checked that the database server was running well


Set define ('wp_use_ext_mysql ', true) in wp-config.php delete

error explanation:


define(‘WP_USE_EXT_MYSQL’, true); Force WP to use MySQL by default instead of MySQL Li
so please delete this line and the problem should be solved.

Otherwise, you can check nd in the PHP 7 configuration_Mysqli extension, and disable mysqli extension – > Select the PHP version.

Read More: