Solving the "Call to Undefined Function mysqli_init()" Error in CodeIgniter on Your Hosting
The dreaded "Call to undefined function mysqli_init()" error in CodeIgniter can be a real headache, especially when you're working on a live hosting environment. This error usually means your CodeIgniter application can't find the necessary MySQLi extension, preventing it from connecting to your database. Let's troubleshoot and fix this problem effectively.
Understanding the Root Cause
The core issue is that the MySQLi extension isn't enabled on your web server. CodeIgniter relies on this extension to interact with MySQL databases. This can happen due to several reasons:
- Missing Extension: The MySQLi extension might not be installed on your server at all.
- Disabled Extension: Even if installed, the extension could be disabled in your server's PHP configuration (
php.ini). - Incorrect PHP Version: You might be using a PHP version that doesn't support MySQLi, or CodeIgniter might be configured to use a PHP version where MySQLi is unavailable.
- Incorrect Configuration: There could be an error in your server's configuration files affecting the extension's loading.
Steps to Resolve the "Call to Undefined Function mysqli_init()" Error
Here's a systematic approach to fix this problem:
1. Verify MySQLi Installation
First, let's confirm whether MySQLi is actually installed on your server. You can do this using a simple PHP file:
Upload this file to your web server and access it through your browser. Look for the "mysql" section in the output. If you see "mysqli" listed under the "mysql" section, it's installed. If not, you'll need to install it (see Step 3).
2. Check PHP Configuration (php.ini)
If MySQLi is installed, the next step is to check if it's enabled. Find your php.ini file. The location varies depending on your server setup. Common locations include:
/etc/php/7.4/apache2/php.ini(or a similar path based on your PHP version and webserver)/etc/php.ini- You can find it using
phpinfo()β it's usually listed on that page
Once you've located the file, open it and search for ;extension=mysqli. If you find this line, remove the semicolon (;) at the beginning to enable the extension. Save the changes and restart your web server. This is crucial; failure to restart will not apply your changes.
3. Installing the MySQLi Extension (If Missing)
If MySQLi isn't installed, you'll need to install it. This requires server-level access and may vary depending on your hosting provider. You might need to use commands like sudo apt-get install php7.4-mysql (replace 7.4 with your PHP version) on a Debian/Ubuntu system, or sudo yum install php74-mysql (replace 74 with your PHP version) on a CentOS/RHEL system. Contact your hosting provider for assistance if you're unsure about this step.
4. Verify PHP Version Consistency
Ensure that the PHP version used by CodeIgniter is the same as the one where you've enabled the MySQLi extension. Inconsistencies here are a common cause of this error.
5. Check Database Credentials
Double-check that your database credentials (hostname, username, password, database name) in your CodeIgniter's database configuration file (application/config/database.php) are correct. Incorrect credentials can lead to errors that might appear like this.
6. Restart Your Web Server
After making any changes to the php.ini file or installing/enabling extensions, it's essential to restart your web server. This applies the changes and makes them effective.
By following these steps, you should be able to successfully resolve the "Call to undefined function mysqli_init()" error and get your CodeIgniter application back up and running. If problems persist, contact your hosting provider for further support. Remember to always back up your files before making any significant changes to your server configuration.
