Common CodeIgniter Issues and Solutions

1. Routing and Controller Not Found Errors

Routes do not resolve correctly, or controllers return 404 errors.

Root Causes:

• Incorrect route definitions in routes.php.
• Case sensitivity issues on Linux-based servers.
• Misconfigured .htaccess file.

Solution:

Ensure correct routing in app/Config/Routes.php:

$routes->get('home', 'Home::index');

Verify case sensitivity on Linux:

ls -l app/Controllers/

Use the correct .htaccess configuration:

RewriteEngine OnRewriteCond %{REQUEST_FILENAME} !-fRewriteCond %{REQUEST_FILENAME} !-dRewriteRule ^(.*)$ index.php/$1 [L]

2. Session Management Issues

Sessions do not persist, expire too quickly, or cause authentication failures.

Root Causes:

• Improper session configuration in Config/Session.php.
• Incorrect permissions on session storage directory.
• Cookie issues preventing session persistence.

Solution:

Set session handler and save path in Config/Session.php:

public $sessionDriver = 'CodeIgniter\Session\Handlers\FileHandler';public $sessionSavePath = WRITEPATH . 'sessions';

Ensure proper permissions for session storage:

chmod -R 777 writable/sessions/

Verify cookie settings in Config/App.php:

public $cookieSecure = false;public $cookieSameSite = 'Lax';

3. Database Connection Errors

CodeIgniter fails to connect to the database, showing SQL errors.

Root Causes:

• Incorrect database credentials in Config/Database.php.
• Database server not running or inaccessible.
• Missing database driver extensions in PHP.

Solution:

Verify database credentials in Config/Database.php:

public $default = [    'DSN'      => '',    'hostname' => 'localhost',    'username' => 'root',    'password' => '',    'database' => 'mydb',    'DBDriver' => 'MySQLi'];

Ensure MySQL service is running:

sudo systemctl start mysql

Enable required PHP extensions:

sudo apt-get install php-mysql

4. CSRF Token Mismatch Errors

Form submissions fail due to CSRF protection errors.

Root Causes:

• CSRF token not included in AJAX requests.
• Session expiration causing token mismatch.
• Improper form submission method.

Solution:

Ensure CSRF token is included in forms:

<input type="hidden" name="csrf_token_name" value="<?= csrf_hash() ?>">

For AJAX requests, add the CSRF token to headers:

$.ajaxSetup({    headers: { 'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content') }});

Disable CSRF protection for specific routes in Config/Filters.php if necessary:

$filters['csrf'] = ['except' => ['api/*']];

5. Deployment Issues

CodeIgniter applications work locally but fail in production.

Root Causes:

• Incorrect environment configuration.
• Permissions issues preventing access to writable directories.
• Base URL not set correctly.

Solution:

Set the correct environment in .env:

CI_ENVIRONMENT = production

Ensure correct permissions for writable/ directories:

chmod -R 775 writable/

Set the correct base URL in Config/App.php:

public $baseURL = 'https://mydomain.com/';

Best Practices for CodeIgniter Development

• Use route caching to improve performance.
• Secure database credentials using environment variables.
• Regularly update CodeIgniter and dependencies.
• Implement proper error logging for debugging.
• Follow best practices for session and CSRF security.

Conclusion

By troubleshooting routing failures, session errors, database connection problems, CSRF token mismatches, and deployment challenges, developers can ensure a stable and efficient CodeIgniter application. Implementing best practices enhances security, performance, and maintainability.

FAQs

1. Why is my CodeIgniter route returning a 404 error?

Ensure correct case sensitivity for controllers, verify route definitions, and check the .htaccess file configuration.

2. How do I fix session issues in CodeIgniter?

Ensure correct session configuration in Config/Session.php, set proper permissions for session storage, and check cookie settings.

3. Why is CodeIgniter not connecting to my database?

Verify credentials in Config/Database.php, ensure the MySQL service is running, and enable required PHP extensions.

4. How do I prevent CSRF token mismatch errors?

Include CSRF tokens in forms, configure AJAX requests properly, and adjust CSRF filters if necessary.

5. What should I check when deploying a CodeIgniter app?

Ensure the correct environment is set, update permissions for writable/ directories, and configure the correct base URL.