Unsupported Plugin Issue: How to Detect and Fix

Unsupported Plugin Issue: How to Detect and Fix

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What Does it Mean “Unsupported Browser Plugin” Issue in the Site Audit?

The “unsupported browser plugin” issue in a site audit typically refers to the use of browser plugins or technologies that are no longer supported by modern web browsers. This can impact the user experience, accessibility, and functionality of a website.

What Triggers This Issue?

The “unsupported browser plugin” issue can be triggered by several factors related to the use of outdated or deprecated technologies. Here are the primary triggers:

1. Use of Deprecated Technologies

Flash content on a website can trigger this issue since modern browsers no longer support Flash.

Similar to Flash, Java applets are deprecated and not supported by modern browsers.

Silverlight is another plugin that has been phased out and is no longer supported.

2. Outdated HTML or Web Standards

HTML Tags for Plugins: Using HTML <object>, <embed>, or <applet> tags to embed unsupported plugins can trigger this issue.

Outdated JavaScript Libraries: Older JavaScript libraries that rely on deprecated plugins or APIs can also cause this problem.

3. Browser Security Policies

Modern browsers have enhanced security policies that block the execution of unsupported or insecure plugins.

Browsers may restrict certain plugins by default, triggering the issue when the website attempts to use them.

4. Lack of Plugin Updates

Plugins that are no longer updated by their developers can become unsupported and trigger this issue. Plugins with known security vulnerabilities are often blocked by browsers, leading to this issue.

5. Operating System Restrictions

Plugins that are specific to certain operating systems (e.g., Windows-only plugins) can cause issues on other platforms. Operating system updates that drop support for certain plugins can also trigger this problem.

6. Third-Party Content

If a website embeds third-party content (e.g., videos, games) that relies on unsupported plugins, this can trigger the issue. Ads using deprecated technologies can cause this issue if they rely on unsupported plugins.

7. Browser Updates

Browser Version Changes: Newer versions of browsers that drop support for certain plugins can trigger this issue if the website hasn’t been updated accordingly.

Security Patches: Security updates in browsers that disable certain plugins for safety reasons can also cause this issue.

How to Check the Issue?

To check if URLs on your portal may be causing this issue, you need to use one of the website SEO analysis remote tools, namely the crawler. Run a site scan, and in the report, you will find all the pages that cause This Site Uses A Plugin That Is Unsupported issue.

In the Sitechecker tool under the ‘Mobile friendly’ category, you’ll notice a particular issue highlighted: ‘Unsupported browser plugins found.’ This issue is critical as it can significantly hinder the user experience on mobile devices.

Unsupported Browser Plugin Issue

By selecting “View issue,” users are directed to a detailed view where they can examine which specific plugins are unsupported and on which pages they are found. This allows webmasters to take corrective action, ensuring their site remains accessible and user-friendly across all devices and browsers.

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How to Fix the Issue?

Fixing the “unsupported browser plugin” issue involves several steps, primarily focused on updating your website to use modern web technologies and ensuring compatibility with current web standards. Here’s a comprehensive approach to address and fix this issue:

1. Identify Unsupported Plugins

Use Sitechecker to identify where unsupported plugins are used.

Check Browser Console: Look for warnings or errors in the browser console that indicate plugin issues.

Browser Console

2. Replace Deprecated Technologies


Replace Flash content with HTML5, which supports video, audio, and interactive content natively.

Example: Use <video> and <audio> tags for multimedia content.

Java Applets

Replace Java applets with JavaScript or modern web technologies that provide similar functionality.


Migrate Silverlight applications to HTML5, JavaScript frameworks (like React or Angular), or other modern web technologies.

3. Update HTML and JavaScript

Use Modern Tags: Replace <object>, <embed>, and <applet> tags with modern equivalents.

Example: For embedding videos, use the <video> tag.

Modern JavaScript Libraries: Use updated and actively maintained JavaScript libraries and frameworks.

4. Ensure Cross-Browser Compatibility

Regularly test your website on different browsers (Chrome, Firefox, Safari, Edge) and devices to ensure compatibility.

Use Polyfills: Implement polyfills to support older browsers if necessary.

5. Enhance Security

Remove plugins known to have security vulnerabilities.

Keep all web technologies and libraries up-to-date with the latest security patches.

6. Leverage Modern Web Development Practices

Design your website to work on all browsers, enhancing the experience with advanced features for modern browsers. Ensure your website is responsive and works well on all device sizes.

7. Provide Alternatives for Unsupported Content

Provide alternative content or functionality for users with browsers that do not support certain features.

Example: If a video cannot be played, provide a download link or a text description.

8. User Notifications

If immediate replacement is not feasible, notify users about the need for certain plugins and provide instructions or alternatives.

Example: Display a message suggesting users switch to a browser that supports the required features.

9. Use Web Standards and Best Practices

Adhere to W3C web standards to ensure broad compatibility and future-proofing. Ensure your site is accessible to all users, including those using assistive technologies.

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