The TokenMismatchException in Laravel occurs when the CSRF token provided in a form submission or AJAX request does not match the CSRF token stored in the session. This is a security feature to protect against cross-site request forgery (CSRF) attacks.

The most common reason for this exception is that the session has expired due to inactivity or the user taking too long to submit the form. When the session expires, the CSRF token in the form becomes invalid, leading to the TokenMismatchException.

To resolve this issue, you can take the following steps:

  1. Increase Session Timeout: You can increase the session timeout to give users more time to fill out forms without encountering the TokenMismatchException. In Laravel, the session timeout is set in the config/session.php configuration file. Look for the lifetime option and adjust it to the desired value in minutes:

    php
    'lifetime' => 120, // Change this value to increase the session timeout
  2. Show a Warning Before Session Expiry: You can display a warning to the user before their session is about to expire. This way, they are aware of the upcoming timeout and have a chance to refresh the page or submit the form again. You can achieve this by using JavaScript to monitor the session timeout and show a warning message.

  3. Handle the Exception: In your application, you can handle the TokenMismatchException gracefully to show a user-friendly error message when it occurs. In Laravel, you can catch the exception in the App\Exceptions\Handler class and display a custom error page or redirect the user to a specific route.

    php
    // app/Exceptions/Handler.php use Illuminate\Session\TokenMismatchException; // ... public function render($request, Exception $exception) { if ($exception instanceof TokenMismatchException) { // Handle the TokenMismatchException here, e.g., redirect to a custom error page return redirect()->route('error.token_mismatch'); } return parent::render($request, $exception); }
  4. Check AJAX Requests: If you are encountering the TokenMismatchException in AJAX requests, make sure you are including the CSRF token in the headers or data of your AJAX requests. You can use the @csrf Blade directive to generate the CSRF token in your forms or extract it from a meta tag in your layout.

By adjusting the session timeout, providing warnings, handling exceptions, and ensuring the CSRF token is included in your AJAX requests, you can effectively manage and mitigate the TokenMismatchException in your Laravel application.

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