How to solve Firefox hangup issues and more

When Firefox won't startup, or you're tormented by crashing or stalling issues, it's understandable that many people consider using a different browser.

Firefox is used by over 362 million users worldwide and is the third most popular browser with a 4.92% market share. If you're a fan, but constant crashing is making you reconsider, before you throw in the towel, take a look at these quick fixes to get your favorite web browser back up and running.

Firefox not working on Mac?

Many Firefox users began to report issues after installing a recent Firefox update. Although there have been no official reports from Firefox, and it's not entirely clear what is causing Firefox's constant crashes, stalling, and unresponsiveness, it's likely linked to the update itself.

The good news is that it's really simple to fix. Jump to the next section as we examine the most common Firefox problems and how to fix them.

Common Firefox hangups and their fixes

We've put together the best fixes for some of the most common Firefox issues. But before we get busy with the troubleshooting steps, head to your main Apple menu and select Restart. 

Glaringly obvious to some but overlooked by many, restarting your Mac can solve so many annoying issues, including browser issues. Give it a go, and if the problem persists, head to the fixes below. We'll get you back to browsing in no time.

What to do when Firefox crashes all the time

Constant crashing and stalling are some of the most annoying browser bugs. Here are a few fixes to help you solve them.

1. Check for Firefox updates

Not running the latest version of Firefox? This could be the reason you're experiencing frequent crashes. Here's how to check:

• Open the browser and select the main Firefox menu > About Firefox.
• If you have an update waiting, press Restart to Update Firefox and wait for the browser to reload.

2. Check for corrupt plug-ins

It's relatively common for third-party extensions and plug-ins to cause browser issues. Try turning yours off and then, one by one, turning them back on. To identify if you have a corrupt extension, follow these steps:

• Open the browser and select Preferences from the main Firefox menu.
• Select Extensions and Themes, bottom left to manage your extensions.
• Toggle them all into the off position and start testing your browser. 
• Turn them on again, one by one, to try and find the culprit.
• If you find a corrupt plug-in, select the three dots next to it and press Remove.

3. Close tabs

How many tabs do you have open right now on your browser? For a few years, Firefox has boasted about its ability to operate with up to 100 tabs open. This may be true, but this undoubtedly will eat away at your Mac resources, slowing your Mac and browser down.

So, close down any tabs you are no longer using, bookmark a few things for later and see if that helps speed up Firefox.

4. Hide intrusive content

Plenty of web pages come packed with content you don't actually need. 

Firefox has a built-in content blocking feature that reduces system resources by restricting third-party tracking content from loading. Here's how to activate it:

1. In Firefox, select the 3 line menu then, Preferences > Privacy & Security.

2. Select the Strict from the list.

3. Restart Firefox.

This option blocks online trackers that may affect the normal functioning of your browser.

5. Clear cookies and cache

An overload of cookies and cache can seriously cause any browser to crash, lag, or in worst cases, even not launch at all. Thankfully it's really easy to clear your browser junk; here's how:

1. In Firefox, select the Library button, top right.

2. Then, History > Clear Recent History.

3. From the dropdown, choose everything, check the Cookies and Cache boxes and press OK. 

6. Refresh Firefox

If, after all of the above, Firefox is still slow on your Mac, try using the Firefox refresh feature; this will clear and reset Firefox, but saves your personal information like open tabs and bookmarks history, saved passwords, and cookies. 

• Open Firefox, in the URL bar type: about:support

• Press enter to go to the Troubleshooting Information page.

• Press the Refresh Firefox button top right.

• Confirm to refresh the browser and restore it to the default settings. 

Restart Firefox once again and test to see if the problem is solved. If not, jump to the next tip.

What to do if Firefox won't startup

If you're unable to launch Firefox, these tips will help you solve the problem.

1. Reset Firefox

There can be many reasons why applications become corrupt, and resetting an application can solve an array of annoying issues. The simplest way to reset an app is by using the Applications feature from the Apple notarized tool CleanMyMac. You'll be able to reset Firefox back to its original state, removing errors along the way. Here's how to do it:

1. Open CleanMyMac — get your free trial here.
2. From the sidebar, select Applications > Scan > Manage My Applications > Uninstaller.
3. Locate Firefox in the list.
4. Click an arrow next to it, select everything except Binaries, and click Remove. 

This way, you can reset Firefox and any other misbehaving app. 

2. Reinstall Firefox

In the unlikely event that a reset doesn't solve your problem, the next step would be to uninstall Firefox and install it once again.

You can do this in two ways. The first one is by using the method above, except this time, selecting Uninstall from the dropdown instead of Reset. The second one is by following the steps below:

• Open Finder > Applications and locate Firefox and drag it to your Trash.
• Select Go > Go to Folder from the top menu.
• Enter the following text and press return:
  ~/Library
• Locate the Caches and Application Support folders and delete any Firefox folders within.
• Finally, reinstall Mozilla Firefox from the official website.

How to solve Firefox not responding 

It's frustrating when your browser becomes unresponsive. Try these tips to bring Firefox back to life.

1. Fix Firefox script errors

• In the search bar, input the following text and press enter:
  about:config 
• Press Accept the Risk and Continue button.
• A search bar will appear. This time, type the following text:
  dom.max_script_run_time
• Select the edit icon, then change the value to 20.
• Press enter to commit the changes; now, restart the browser and test again.

2. Check for malware

An unresponsive browser can often be a sign of malware. You can use the app I mentioned previously in the article, CleanMyMac, to perform an in-depth system scan via its intelligent Protection feature. Not only can this clever tool remove the threats detected, but it can also provide real-time protection against malicious viruses. Here's how to scan your Mac for malware:

1. Launch the application and select Protectionfrom the sidebar.
2. Press Scan.
3. Once complete, if malware is found, follow on-screen instructions to remove it.

Although our Macs come with Apple's basic malware detection service, XProtect, it's important to remember this isn't enough to keep our Macs secure and safe from ever-advancing threats. Apple is great at what it does, but it isn't a dedicated security company, so leave your anti-virus needs to the third-party experts.

What does "A copy of Firefox is already open" mean?

If you keep receiving an error message when you launch Firefox that says, "A copy of Firefox is already open," you'll need to delete your browser profile. Here's how:

• Open a Finder window from the top menu and select Go > Go to Folder.
• Type in the below text and press enter:
  ~/Library
• Locate the Application Support folder > Firefox > Profiles.
• If the .parentlock file exists, send it to your Trash.
• Restart the browser and test.

We might have reached the end of this article, but now you know exactly what to do if you can't get Firefox to open. Stick with us for more awesome tutorials, tips, and troubleshooting guides — happy browsing.