WebAssembly not working after privacy settings?

After changing privacy settings, a web app may stop loading, show an error, or fail when it tries to run a feature. That does not automatically mean WebAssembly is disabled. Most current browsers support it, while an extension, a browser policy, or a site-specific restriction may interfere with the page.

Use Browser Info to check whether your current browser reports WebAssembly support. Then compare the result with the site that is failing, and make one change at a time so you can identify the cause.

Recheck WebAssembly support

1. Open Browser Info in the same browser and profile where the problem occurs. Check its supported features for WebAssembly.
2. Note whether the feature is reported as available. Also note your browser and version, which Browser Info displays, so you can compare later.
3. Open the affected website in a new tab and reload it. If it offers a feature that depends on WebAssembly, try that feature rather than relying only on whether the page opens.
4. If the page still fails, open it in a private or incognito window and check it again. Some extensions do not run in private windows, which can help you spot an extension conflict.
5. Return to Browser Info after testing, or open it in the private window too. Compare the WebAssembly result and the privacy information between the two browser sessions.

Keep the browser, device, and network the same while comparing results. If you change several settings or switch browsers at once, it becomes harder to tell what affected the page.

What the result means

WebAssembly is reported as available

Your browser exposes WebAssembly support to the test page. This does not prove that every website can use it: the site may have a script error, a security rule, or another browser feature requirement. If Browser Info reports support but one site fails, focus on that site's settings, extensions, and error message rather than changing system privacy controls.

WebAssembly is unavailable in both normal and private windows

The browser may be outdated, managed by an organization, using a hardened configuration, or running in an environment that limits browser features. A virtual desktop or restricted work profile can also behave differently from a personal browser. Update the browser if you can, then ask the device administrator whether a policy limits WebAssembly.

It works in a private window but not in your regular window

This points to something tied to your regular browser profile, such as an extension, a site-specific setting, or stored site data. Private mode itself does not normally turn WebAssembly off. It simply gives you a useful comparison because it can use a different set of extensions and site data.

Browser Info says it is available, but the website still fails

Support is only one part of the check. The site could be blocked from running scripts, its own code could have failed to load, or a content blocker could have stopped a required file. Check the browser's site settings and the page's own error message before assuming that the browser lacks WebAssembly.

How to fix it

1. Reload the page and restart the browser. Close the failing tab, open a fresh one, and test again. If the browser has been running for a long time, quit it fully before reopening it.
2. Check extensions and content blockers. Temporarily pause a privacy or script-blocking extension for the affected site, then reload. In Chrome or Edge, open Extensions › Manage extensions. In Firefox, open Menu › Add-ons and themes. In Safari on macOS, open Safari › Settings › Extensions. Turn off one extension at a time and restore it if it makes no difference.
3. Review site settings. In Chrome or Edge, open Settings › Privacy and security › Site settings and check whether the affected site has an unusual permission or restriction. In Firefox, open Settings › Privacy & Security and review your tracking protection and site exceptions. In Safari on macOS, open Safari › Settings › Websites and review any site-specific rules that apply. Menu names can vary slightly by browser version.
4. Check whether scripts are allowed. WebAssembly support does not bypass a site's need to run its scripts. In Chrome or Edge, check the JavaScript setting under Settings › Privacy and security › Site settings. In Firefox, review content-blocking extensions and any site-specific exceptions. In Safari, check content blockers for the affected site. Only change a setting for a site you trust.
5. Update the browser or check its management policy. Install the latest available browser update and restart. If this is a work or school device, a policy may control browser features. Ask the administrator before changing managed settings.

On Windows 11, Settings › Privacy & security controls operating-system privacy permissions, not a general WebAssembly switch. On macOS, System Settings › Privacy & Security also does not provide a WebAssembly toggle. For this issue, check the browser and its extensions first.

What the browser test cannot confirm

Browser Info checks what the browser reports about supported features and privacy. It cannot prove that a particular website's WebAssembly code loaded correctly, that the site is safe, or that an extension did not block a specific file. A feature can be supported by the browser while the website still fails for a separate reason.

For a broader overview of the feature and the checks involved, see WebAssembly support for a web developer demo. If the test and site disagree, record the browser version, whether you used a regular or private window, and which extensions or site rules changed. That gives support staff a clearer starting point without requiring you to disable privacy protections across the browser.