Fatal Error Uncaught Error Call To Undefined Function Mysql_Connect


In the ever-evolving landscape of web development, dealing with errors is part and parcel of the job. One of the most perplexing and common errors developers encounter is the “Fatal Error: Uncaught Error: Call to Undefined Function mysql_connect.” This error can halt your project and lead to frustration if not addressed correctly. In this comprehensive guide, we will unravel the intricacies of this error, understand its causes, and explore solutions to get your project back on track.

Understanding the Fatal Error

Before delving into the depths of this error, let’s start with the basics. The error message, “Fatal Error: Uncaught Error: Call to Undefined Function mysql_connect,” may seem daunting, but it essentially means that PHP is unable to find and execute the mysql_connect function.

This error has become more prevalent in recent years due to changes in PHP and the deprecation of the mysql_ functions. PHP developers are transitioning to improved database connection methods, such as MySQLi (MySQL Improved) and PDO (PHP Data Objects).

The Causes of the Error

Now that we know what the error message means, let’s explore the primary causes behind this issue.

1. Deprecated mysql_ Functions

The foremost reason for encountering this error is the use of deprecated mysql_ functions. These functions, including mysql_connect, have been removed in PHP 7 and later versions. If your codebase relies on these outdated functions, you will encounter the “Fatal Error.”

2. Incompatible PHP Versions

The version of PHP you’re using can also be a contributing factor. If your project was developed using an older version of PHP that supported the mysql_ functions, but you’re trying to run it on a newer PHP version, you’ll encounter this error.

3. Missing PHP Extensions

Sometimes, the necessary PHP extensions are not installed or enabled on the server. The mysql_connect function requires the MySQL extension to be installed and configured correctly.

Resolving the Fatal Error

Now that we’ve identified the root causes, let’s explore how to resolve the “Fatal Error: Uncaught Error: Call to Undefined Function mysql_connect.”

1. Upgrade Your Code

The most sustainable solution is to update your code to use modern database connection methods like MySQLi or PDO. These methods are not only more secure but also compatible with the latest PHP versions.

2. Check PHP Version

Ensure that the PHP version you’re using is compatible with your codebase. If you’re running an older PHP version, consider upgrading to a newer one that supports the updated database functions.

3. Verify MySQL Extension

Confirm that the MySQL extension is installed and enabled on your server. If not, you may need to install it or ask your hosting provider to do so.

Migrating to MySQLi

Let’s take a closer look at migrating to MySQLi, which is a popular and reliable alternative to the deprecated mysql_ functions.

1. Updating Connection Code

Replace your mysql_connect code with the following:

$servername = "your_server_name";
$username = "your_username";
$password = "your_password";
$dbname = "your_database_name";

// Create a connection
$conn = new mysqli($servername, $username, $password, $dbname);

// Check the connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);

2. Database Queries

Adapt your database queries to use the MySQLi functions, which are similar to the mysql_ functions but more secure and compatible.


The “Fatal Error: Uncaught Error: Call to Undefined Function mysql_connect” can be a stumbling block in your web development journey. However, by understanding its causes and implementing the appropriate solutions, you can swiftly overcome this obstacle. Migrating to modern database connection methods like MySQLi is not only a solution but also a step towards enhancing the security and efficiency of your web applications. So, embrace the change, update your code, and continue building remarkable web experiences.