If you’ve been using LearnDash to power your online courses, you already know how versatile the platform can be. However, you might occasionally encounter issues with quizzes freezing, hanging, or failing to complete. These issues can frustrate your learners and disrupt their learning experience. Fortunately, most of these problems can be resolved with some targeted troubleshooting.

Here’s a comprehensive guide to fixing LearnDash quiz issues, starting with the most common solution:

1. Increase the WordPress Memory Limit

LearnDash quizzes rely heavily on server resources. If your WordPress memory limit is too low, it can cause quizzes to hang or fail to process correctly.

Solution: Increase the PHP memory limit in your WordPress installation. You can do this by editing your wp-config.php file and adding the following line:

define( 'WP_MEMORY_LIMIT', '256M' );

This increases the memory limit to 256MB, which is generally sufficient for LearnDash quizzes to function smoothly. If you’re on a shared hosting plan, you might need to contact your hosting provider to confirm or increase the limit.

If this fails to work, it’s worth trying a limit of 512M before moving on to another suggestion.

2. Disable Caching for Quizzes

Caching plugins and server-side caching can interfere with LearnDash quizzes. Cached quiz data may prevent users from progressing or submitting their results.

Solution: Exclude LearnDash quiz pages from your caching solution. If you’re using a popular caching plugin like WP Rocket, W3 Total Cache, or LiteSpeed Cache, look for the option to exclude specific URLs or post types from caching. Add your quiz pages or LearnDash URLs to this exclusion list.

Additionally, check with your hosting provider if server-side caching (such as Varnish) is enabled and ensure it’s bypassed for quiz pages.

3. Address WP Login Cookie Expiration

WordPress relies on cookies to maintain user sessions. If the cookie expires while a user is taking a quiz, it can cause the quiz to hang or fail to save progress.

Solution: Extend the login session duration in WordPress. Add the following code snippet to your functions.php file to increase the login cookie expiration time:

add_filter( 'auth_cookie_expiration', function() {
    return YEAR_IN_SECONDS; // One year in seconds
} );

Alternatively, you can use MONTH_IN_SECONDS for a month-long expiration or WEEK_IN_SECONDS for a week-long expiration, depending on your site’s requirements. This adjustment ensures users remain logged in for a longer period, preventing session-related disruptions.

4. Check for JavaScript Errors

JavaScript plays a crucial role in powering LearnDash quizzes. Errors in your site’s JavaScript can cause quizzes to behave unpredictably or fail to complete.

Solution: Use your browser’s developer tools to inspect for JavaScript errors. Open the quiz page, right-click, and select Inspect or press F12. Navigate to the Console tab and look for red error messages. These errors often point to conflicts with other plugins or custom code. Disable recently added plugins or scripts to identify the source of the issue.

5. Inspect the AJAX Response

LearnDash quizzes use AJAX to submit answers and load new questions dynamically. If the AJAX response is failing, it could indicate a deeper issue.

Solution: In your browser’s developer tools, go to the Network tab and filter for XHR requests. Reload the quiz page and monitor the AJAX requests as you interact with the quiz. If you see errors or failed requests, click on them to view the response. This can help you pinpoint server or configuration issues.

6. Enable WP Debug Mode and Check PHP Error Logs

When quizzes fail, there might be server-side PHP errors causing the issue. Debugging these errors can provide critical insights.

Solution: Enable WordPress debug mode by adding the following lines to your wp-config.php file:

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );

This creates a debug log file (/wp-content/debug.log) where PHP errors are recorded. Check this file for errors related to LearnDash or your server configuration. Setting WP_DEBUG_DISPLAY to false ensures errors are not displayed on the front end, preventing exposure of sensitive information. Once debugging is complete, remember to disable debug mode.

7. Ensure Server Resources Are Adequate

Shared hosting environments can sometimes struggle with the demands of LearnDash quizzes. If your hosting plan is underpowered, it could lead to freezing or failed submissions.

Solution: Upgrade to a hosting plan optimized for WordPress and e-learning platforms. Managed WordPress hosts like Kinsta, SiteGround, or Rapyd.cloud often provide better performance for resource-intensive plugins like LearnDash.

8. Update LearnDash and Related Plugins

Outdated versions of LearnDash or related plugins may contain bugs that have been fixed in newer releases. Compatibility issues with the WordPress core or other plugins can also arise.

Solution: Ensure LearnDash and all your plugins are up to date. Also, verify that your WordPress version is compatible with your installed LearnDash version.

9. Test with a Default Theme

Sometimes, conflicts with custom themes can cause quiz-related problems.

Solution: Switch to a default WordPress theme like Twenty Twenty-Three and test the quizzes. If the issue is resolved, it’s likely that your theme is causing the conflict. Reach out to your theme developer for support.

10. Check for Plugin Conflicts

Conflicts with other plugins, especially those related to quizzes or e-learning, can cause LearnDash quizzes to hang or fail.

Solution: Deactivate all other plugins except LearnDash and its add-ons. Test your quizzes to see if the issue persists. If the problem resolves, reactivate your plugins one by one to identify the conflicting plugin. Pay special attention to plugins that modify quiz behavior or add custom functionality to LearnDash.

11. Verify Stable Internet Connection

An unstable internet connection during a quiz submission can cause it to fail, as LearnDash may not retry the submission due to limitations in its logic.

Solution: Ask users to ensure they have a stable internet connection before starting a quiz. If they report issues, encourage them to retry on a more reliable connection. Additionally, consider providing a brief warning or guideline on your quiz instructions page to highlight the importance of stable connectivity.

Conclusion

LearnDash quiz freezing or completion issues can stem from a variety of sources, including server limitations, plugin conflicts, or misconfigurations. By following the steps above, you can systematically identify and resolve the problem, ensuring a smooth experience for your learners.

If you’re looking for additional ways to enhance LearnDash or need specialized plugins to supercharge your e-learning platform, check out our suite of LearnDash plugins designed to improve performance, usability, and learner engagement.

Got questions or need assistance? Contact us today and let our experts help you make the most of LearnDash!