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Fixing JavaScript Errors After Installing Autoptimize: A Troubleshooting Guide

17 threads Sep 16, 2025 Plugin → Autoptimize

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If you've installed the Autoptimize plugin and suddenly see errors like Uncaught ReferenceError: popupTriggerClick is not defined or a critical feature on your site stops working, you're not alone. This is one of the most common issues users face when they first enable JavaScript optimization. This guide will explain why this happens and walk you through the steps to resolve it.

Why Do These JavaScript Errors Occur?

Autoptimize works by aggregating, minifying, and sometimes deferring your site's JavaScript files. This process is incredibly effective for boosting performance. However, it can sometimes change the order in which scripts are loaded or how they interact with each other. If one script depends on another (for example, a popup script depends on a library like Popper.js), and that dependency is loaded out of order or deferred, the first script will fail, throwing a ReferenceError.

Step-by-Step Troubleshooting

Follow these steps to identify and fix the problem. It's best to do this on a staging site first, but if that's not possible, you can do it on your live site during a period of low traffic.

Step 1: Identify the Culprit

The first step is to figure out which part of Autoptimize's optimization is causing the conflict.

  1. Go to Settings → Autoptimize in your WordPress dashboard.
  2. Start by disabling only the "Optimize JavaScript Code?" option. Save changes and clear Autoptimize's cache.
  3. Check your website. If the error is gone and the feature works, you've confirmed the issue is with JavaScript optimization. You can stop here if performance is acceptable, or proceed to the next step to try a more optimized configuration.
  4. If the error persists, re-enable JS optimization and test by disabling the other options one by one (CSS, HTML, Images) to rule them out.

Step 2: Try Alternative JS Settings

If JavaScript optimization is the problem, you don't necessarily have to leave it off entirely. Try these alternative configurations:

  1. Enable "Optimize JavaScript Code?" but disable the "Aggregate JS-files?" option. This minifies the code but doesn't combine all files into one, which can resolve ordering issues.
  2. If that works, you can also try enabling the "Defer JavaScript?" option (often found under "Extra" settings) while keeping aggregation off. This can help with render-blocking issues without breaking scripts.

Step 3: Exclude the Problematic Scripts

If the above steps don't work, the most reliable solution is to exclude the specific JavaScript files that are causing the error from being optimized. This is a very common fix.

  1. Go to Autoptimize → JS, CSS & HTML → Javascript Options.
  2. In the "Exclude scripts from Autoptimize:" field, you can add specific paths. The threads show that common exclusions often include:
    • Plugin-specific scripts: wp-content/plugins/plugin-name/ (e.g., wp-content/plugins/pdf-embedder/)
    • Theme-specific scripts: wp-content/themes/your-theme-name/
    • Specific libraries: js/jquery/jquery.js (often excluded by default)
  3. To find the exact path, look at the browser console error. It will often reference a file path that you can use in the exclusion field. Add one exclusion at a time, save your settings, clear the cache, and test.

Checking the Browser Console

Knowing how to check your browser's console for errors is key to troubleshooting. Here’s how:

  1. Right-click on your webpage and select Inspect.
  2. Click on the Console tab.
  3. You will see any JavaScript errors listed in red. These messages are the best clue for figuring out what script is failing and what needs to be excluded.

Conclusion

JavaScript errors after enabling Autoptimize are almost always solvable through careful troubleshooting. The process almost invariably involves:

  1. Disabling optimizations to confirm the issue.
  2. Testing less aggressive optimization settings.
  3. Excluding the specific scripts that are causing the conflict.

By following this methodical approach, you can enjoy the significant performance benefits of Autoptimize while keeping all your site's functionality intact.

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