HomeFixesHow to Fix Firefox Browser Error NS_ERROR_INTERCEPTION_FAILED

How to Fix Firefox Browser Error NS_ERROR_INTERCEPTION_FAILED



Have you ever seen the error “NS_ERROR_INTERCEPTION_FAILED” pop up randomly in Firefox? Pages not loading images or content properly? Welcome to the club!

Don’t worry, this blog post will take a deep dive into what that Firefox issue means and how you can banish it for good.

Photo credit: Growtika.Unsplash

What’s Causing This Crazy Error Message NS_ERROR_INTERCEPTION_FAILED on Firefox Browser?

The NS_ERROR_INTERCEPTION_FAILED error on Firefox typically pops up when something goes wrong with service workers in Firefox. Service workers are little scripts that let sites cache resources locally and work offline.

But when they intercept requests and fail to respond properly, you get this Firefox browser error.

Service Workers on Firefox – A Brief Explainer

Not sure what service workers are all about? Here’s a quick primer:

  • Registered by websites to cache resources locally.
  • Help sites work offline or load faster.
  • Intercept network requests and can modify responses.
  • Persist between page loads and when browser closed.
  • Firefox stores them like cookies.

Now that we know what they are, let’s move on to…

Nine Ways to Troubleshoot and Fix The NS_ERROR_INTERCEPTION_FAILED Error on Firefox

When NS_ERROR_INTERCEPTION_FAILED rears its ugly head, try these steps to fix the Firefox error.

Disable Those Firefox Browser Extensions!

Image credit: Mozilla Firefox

Browser extensions like ad blockers and privacy tools often block service workers from working properly. Try disabling them and see if it fixes things.

Purge All Service Workers on Firefox Browser

Head to Firefox settings and disable service workers entirely. Browse to the site and see if the error goes away when no service workers are active.

Inspect the Site’s Service Worker Code

Dig into the service worker JavaScript file itself and see if you spot any obvious errors in how it handles intercepted requests.

Use Private Browsing Mode on Firefox Browser

Private mode doesn’t use service workers. If the site works fine there, it points to a bad service worker.

Clear All the Things – Clear Firefox Browser Cookies, Cache and Data

Cookies, cache, site data – clear it all out to remove any stored service workers.

Update Your Firefox Browser

Image credit: Mozilla Firefox

Can’t hurt to update Firefox in case a bug fix was pushed out.

Whitelist the Site

If using something like NoScript, whitelist the site to allow service workers.

Try Firefox Beta or Nightly Builds

More recent builds may have additional service worker bug fixes.

Report Issues to Mozilla Customer Service

If all else fails, report it to Mozilla so they can investigate further.


Photo credit: Clker-Free-Vector-Images/Pixabay

Got additional questions about NS_ERROR_INTERCEPTION_FAILED? Here are some frequent ones:

Why does this error happen randomly on some sites?

It’s likely the service worker code has some intermittent bugs that surface under certain conditions. Complex code often leads to odd edge case errors.

Will this error go away on its own eventually?

Probably not. Without taking action to remove bad service workers, the error will persist.

Is this error a risk to my security or privacy?

Not directly. It’s just a symptom of something gone wrong with the site’s service worker functionality.

Does this happen in other browsers like Chrome?

NS_ERROR_INTERCEPTION_FAILED is specific to Firefox. But Chrome and others could show different errors for similar issues.

Can I prevent this by disabling service workers completely?

You can, but you’d lose out on the benefits like offline access. Better to fix the root cause.



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