A fairly common situation: you double-clicked the Mozilla Firefox shortcut on your desktop or opened this application from the taskbar, but are faced with the fact that the browser refuses to start.

Unfortunately, the problem when the Mozilla Firefox browser refuses to launch is quite common, and its occurrence can be influenced by a variety of reasons. Today we will look at the main reasons, as well as ways to resolve problems with launching Mozilla Firefox.

Option 1: "Firefox is running and not responding"

One of the most common Firefox crash situations is when you try to launch the browser but instead get a message "Firefox is running and not responding" .

Typically, a similar problem appears after a previous incorrect closing of the browser, when it continues to execute its processes, thus preventing a new session from starting.

First of all, we will need to end all Firefox processes. To do this, press the keyboard shortcut Ctrl+Shift+Esc , to open "Task Manager" .

In the window that opens, you will need to go to the tab "Processes" . Find the Firefox process (“firefox.exe”), right-click on it and select the option from the context menu that appears "Cancel task" .

If you find other processes associated with Firefox, you will need to kill them as well.

After completing these steps, try launching your browser.

If Mozilla Firefox still won't start and still shows the error "Firefox is running and not responding", then in some cases this may indicate that you do not have the necessary access rights.

To check this, you will need to get into your profile folder. It is, of course, easier to do this using Firefox itself, but given that the browser does not start, we will use another method.

Press a combination of keys on your keyboard Win+R. The Run window will appear on the screen, in which you will need to enter the following command and press Enter:

%APPDATA%\Mozilla\Firefox\Profiles\

A folder with profiles will be displayed on the screen. Typically, if you have not created additional profiles, you will only see one folder in the window. If you use several profiles, then for each profile you will need to perform further actions individually.

Right-click on the Firefox profile and in the context menu that appears, go to "Properties" .

A window will appear on the screen in which you will need to go to the tab "Are common" . At the bottom of the window, make sure you have the option checked. "Only for reading" . If there is no checkmark (dot) next to this item, you must set it yourself and then save the settings.

Option 2: “Error reading configuration file”

If the message appears on the screen after you try to launch Firefox "Error reading configuration file" , then this means that there is a problem with the Firefox files, and the easiest way to solve the problem is to reinstall Mozilla Firefox.

First of all, you will need to completely remove Firefox from your computer. We have already talked about how this task can be accomplished in one of our articles.

Open Windows Explorer and delete the following folders:

C:\Program Files\Mozilla Firefox

C:\Program Files (x86)\Mozilla Firefox

And only after you complete the removal of Firefox, you can start downloading the new version from the official website of the developer.

Option 3: “Error opening file for writing”

This type of error is usually displayed in cases where you use an account on your computer without administrator rights.

Accordingly, in order to solve the problem, you need to obtain administrator rights, but this can be done specifically for the application being launched.

Just right-click on the Firefox shortcut on your desktop and in the context menu that appears, click on "Run as administrator" .

A window will appear on the screen in which you will need to select an account that has administrator rights, and then enter its password.

Option 4: “Your Firefox profile could not be loaded. It may be damaged or inaccessible."

An error like this clearly hints to us that there are problems with the profile, for example, it is inaccessible or completely absent on the computer.

Typically, a similar problem occurs if you have renamed, moved, or even deleted the Firefox profile folder.

Based on this, you have several ways to solve the problem:

1. Move the profile to its original location if you have moved it before;

2. If you renamed the profile, then you need to give it the same name;

3. If you cannot use the first two methods, then you will need to create a new profile. Please note that by creating a new profile, you will get a clean Firefox.

To start creating a new profile, open the “Run” window using the keyboard shortcut Win+R . In this window you will need to run the following command:

firefox.exe -P

The Firefox profile management window will appear on the screen. We will need to resort to creating a new profile, so click on the button "Create" .

Enter a name for the profile, and also, if necessary, in the same window, specify the location on the computer where the folder with the profile will be stored. Finish creating your profile.

The Firefox profile management window will reappear on the screen, in which you will need to highlight the new profile and then click on the button "Start Firefox" .

Option 5: Error saying Firefox has crashed

A similar problem appears when you launch the browser. You may even see its window appear, but suddenly the application closes and a message indicating that Firefox has crashed is displayed on the screen.

In this case, Firefox can crash due to various factors: viruses, installed add-ons, themes, etc.

First of all, in this case you will need to scan using your antivirus or a special cleaning utility, for example, Dr.Web CureIt.

After performing the scan, be sure to restart your computer and then check the functionality of your browser.

If the problem persists, then you should try to completely reinstall the browser, first completely removing the web browser from the computer.

After the uninstallation is complete, you can begin installing the latest version of the browser from the developer’s official website.

Option 6: "XULRunner Error"

If you see the “XULRunner Error” error on your screen when you try to launch Firefox, this may indicate that you have an outdated version of Firefox installed on your computer.

You will need to completely remove Firefox from your computer, which we have already talked about on our website.

After completely removing the browser from your computer, download a new version of the web browser from the official website of the developer.

Option 7: Mozila does not open, but does not display an error

1) If the browser was working fine before, but at some point stopped launching, the most effective way to fix the problem is to perform a system restore.

This procedure will restore the system to the time when the browser was working correctly. The only thing this procedure will leave is user files (documents, music, photos and videos).

To start the system rollback process, open the menu "Control Panel" , set the top right corner to view mode "Small Signs" and then open the section "Recovery" .

In the window that opens, select "Run System Restore" and wait a few moments.

Select a suitable rollback point to when Firefox was working fine. Please note that depending on changes made since then, system recovery may take several minutes or several hours.

2) Some antivirus products may cause problems with Firefox. Try pausing them and checking if Firefox is working.

If, according to the results of the scan, the cause was an antivirus or other security program, you will need to disable the network scanning function or other function related to the browser or network access.

3) Try running Firefox in Safe Mode. To do this, hold down the Shift key and click on the browser shortcut.

If the browser starts normally, then this indicates a conflict between the browser and installed extensions, themes, etc.

First, disable all browser add-ons. To do this, click on the menu button in the upper right corner, and then in the window that appears, go to the section "Extras" .

In the left pane, go to the tab "Extensions" , and then disable all extensions. It would be useful if you completely delete them from the browser.

If you have third-party themes installed for Firefox, try reverting to the default theme. To do this, go to the tab "Appearance" and make a theme "Standard" default theme.

Finally, try turning off hardware acceleration. To do this, open the browser menu and go to the section "Settings" .

In the left pane of the window, go to the tab "Additional" and then open the subtab "Are common" . Here you will need to uncheck the box “Use hardware acceleration whenever possible” .

After completing all the steps, open the browser menu and click on the icon in the lower area of ​​the window "Exit" . Try launching your browser normally.

4) Reinstall your browser and create a new profile. How to accomplish this task has already been discussed above.

And a small conclusion. Today we looked at the main ways to fix problems starting the Mozilla Firefox browser. If you have your own method for fixing the problem, share it in the comments.

This article describes what to do if Firefox doesn't open when you click the Firefox icon.

• If you get a message you can dismiss (e.g. "TypeError: Components.classes["@ ... ;1"] is undefined", "onload error TypeError: ...", "Exc in ev handl: ...") and can open Firefox, see .
• If Firefox starts but won't load any websites, see Websites don't load - troubleshoot and fix error messages.

Firefox is already running but is not responding

Your Firefox profile cannot be loaded. It may be missing or inaccessible

Failed to read the configuration file

This error is caused by a problem with Firefox program files. The solution is to remove the Firefox program and then reinstall Firefox. (This will not remove your passwords, bookmarks or other user data and settings which are stored in a separate folder.)

1. Delete the Firefox installation directory, found in one of these locations by default:
   • C:\Program Files\Mozilla Firefox
   • C:\Program Files (x86)\Mozilla Firefox
2. Use another browser to download the Firefox installer from the Firefox download page and install it. See How to download and install Firefox on Windows for details.

XULRunner - Error

If you see the message, "XULRunner - Error: Platform version is not compatible with minVersion "" ("" depends on version number), after a software update, use another browser to download the Firefox installer from the Firefox download page , save it to the desktop or other location, delete the Firefox installation directory and then reinstall Firefox.

There was an error launching the application

This error indicates that either Firefox is not installed or your shortcut to it is incorrect. Make sure that Firefox is installed at the location specified by the shortcut. If it isn't, install Firefox if necessary, then modify the shortcut to point to the correct location.

Error opening file for writing…

If you receive the above error when launching Firefox on a Windows system, you may be required by Firefox to log in as an administrator. You can either reboot the computer or, if you have an administrator account, you can execute the program as an administrator.

1. Find the firefox.exe program file in the Firefox application folder on your system.
2. Right-click the icon.
3. Select Run As...Select Run As Administrator… . Select The following user:. From the User name drop-down, select Administrator or another user that has administrator privileges. Enter the password required to log in to this account. Click OK.
4. The Firefox application is started using the administrator Windows account. The user that was used to log in to Windows at startup is still the active one.

Other error messages

If you get another error message (e.g. "XML Parsing Error: undefined entity Location", "Secure Connection Failed…uses an invalid security certificate"), see Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.

No error message

If you click the Firefox icon but no Firefox window opens and no error message is shown, a simple first step is to restart your computer and then try again. If Firefox still does not start, see the following sections.

Firefox will not start after updating

• If you use certain versions of ZoneAlarm or other Internet security software that includes a "Virtual Browsing" feature, it can prevent Firefox from starting. Check virtualization settings and clear the virtual cache, if your Internet security software includes this feature, or visit the software provider"s support site for more help.
• Firefox may fail to start for some Windows users after updating, if AVG or AVAST antivirus is installed. For details, see this Techdows article.

Firefox will not start after installing add-ons

If Firefox previously worked but stopped after you installed extensions or themes, see

It is difficult to imagine a modern user who would not work with Internet browsers. These utilities help you go online and browse websites. Through them, files and other data are downloaded. The variety of Internet browsers is surprising. A utility called Mozilla Firefox is in great demand. This application is not immune to crashes and problems. Sometimes it turns out that Firefox does not start. What to do under such circumstances? What can lead to disruption of the Internet browser? How to make the browser work? We will try to answer all these questions further. As a rule, a browser failure to function normally is not critical for the operating system. Only information stored in the Internet browser may be affected.

No answer

Doesn't start? This problem is not that rare. It can cause a lot of problems for the user.

Sometimes it happens that the browser starts and does not respond. The application stops responding to user commands. What should I do?

Typically, this situation occurs if the Internet browser was completed incorrectly during the previous session. Or Firefox does not start and freezes due to an operating system failure.

1. Press Ctrl + Alt + Del on your keyboard.
2. Select the "Task Manager" line in the window that appears.
3. Open the "Processes" tab.
4. Select "Mozilla" and click on the "End process" button.

Access rights

Why won't Firefox launch? The reasons for this phenomenon may be different. Therefore, we will consider only the most common scenarios.

Is Mozilla running and not responding? This situation is sometimes caused by a lack of access rights to applications.

Firefox won't start? Hangs in processes and does not respond? You can try to get access rights to the utility. To do this you will need:

1. Press Win + R, or open Start and place the cursor in the search bar.
2. Write the address in the line that appears. It is listed under the manual.
3. Right-click on the folder with the profile name "Mozillas" and select the "Properties" section.
4. Open the "General" block and uncheck the "Read-only" attribute.
5. Save changes.

As soon as the adjustments take effect, you can launch the Internet browser. The problem with the work of Mozilla should disappear.

The address to go to the Firefox root folder looks like this:

%APPDATA%\Mozilla\Firefox\Profiles\.

Configuration errors

Firefox won't start? If, when you try to work with the application, a browser configuration error message appears on the screen, this means that the problem lies in the Mozilla files. Such failures occur for various reasons.

What to do? It is best to reinstall the application. Typically, users act according to the following instructions:

1. Find the latest version of Mozilla using any Internet browser and download it to your computer.
2. Go to “Start” - “Control Panel” - “Uninstall programs”.
3. Select "Mozilla" in the menu that appears and click on the "Delete" operation.
4. Follow the instructions of the "Uninstallation Wizard".
5. Run the Firefox installation file.
6. Complete the installation of the application by following the prompts on the monitor display.

Important: when deleting an old version of the Internet browser, it is better to give preference to complete uninstallation. All saved tabs, passwords and addresses will have to be erased from the OS.

Errors reading files to write

Why won't Mozilla Firefox launch? There is no clear answer to such a question. The browser is an application that can stop working for many reasons.

Sometimes when you start the Internet browser, an error reading a file to write appears on the screen. This situation is not common. It involves using an account without administrator rights.

To get Mozilla working, you will either have to change your account or act like this:

1. Right-click on the Firefox shortcut.
2. Select the "Run as administrator" operation.
3. Click "Ok" or "Run".

Now we just have to wait a little. After a few seconds, the Internet browser should start. From now on you can work with him. If the error repeats, you will have to use the above instructions.

Error loading profile

Firefox won't start? On the monitor display does the user see a message about an error loading the utility profile?

A similar problem occurs if the Internet browser account is damaged or completely missing from the operating system. This occurs either due to a virus infection of the PC, or through user actions. Renaming folders and making adjustments to files in the corresponding ones results in a download error.

The situation can be corrected in different ways. Here are the most common tips that will help you cope with the task:

1. Restore the profile to the Mozilla root folder.
2. Return the profile to its original name if it has been changed.
3. Create a new account. In this case, the user will receive a "clean" Firefox.
4. Scan your computer for viruses and remove all malicious files.

If such manipulations do not help, the surest, fastest and most reliable solution is to reinstall the Internet browser. We have already talked about how to carry it out.

How to create a profile

A few words about how you can create a new account in Mozilla Firefox. Not every user knows about this technique.

To create a “clean” Mozilla profile you will need:

1. Open a command prompt and write Firefox.exe -P.
2. Click on "Run" or Enter.
3. Select the "Create..." command.
4. Give the new profile a name.
5. Select a location to save the data.
6. Select the created account in the window that appears and click on “Launch Firefox”.

It is done. When you start Mozilla, a “clean” profile will be used. Nothing difficult or unclear! Even a novice PC user can cope with the task!

Browser crash

Mozilla Firefox won't start? As you can already see, users are faced with a variety of Internet browser errors. Depending on the message displayed on the screen, the further algorithm of actions will change.

Quite often, users see warnings about the fall of Mozilla. They are called "crashes". As a rule, in this case, the browser processes slow down, after which the utility stops responding to user actions. After a while, the browser closes and a “crash” message appears on the screen.

The error can be caused by anything - from a system failure to a virus infection of the PC. If problems occur immediately after installing Mozilla, you may suspect that the program was installed incorrectly.

What to do? You can correct the situation if you find out the cause of the problems. Here are the most effective techniques for dealing with crashes:

1. Reinstall Mozilla Firefox after completely uninstalling the program.
2. Scan your computer for viruses and spyware. To do this, you will need any antivirus (Kaspersky, Avast, NOD32 and others) and SpyHunter 4. If dangerous objects are detected, they must be disinfected or removed from the operating system.

As a rule, all of the above techniques allow you to quickly get your Internet browser working. The tips presented to your attention are suitable for all browsers.

Old version

Why won't Firefox launch? Another problem that PC users face is the XULRunner type error. Fortunately, it is becoming less and less common.

A message like this indicates that you are using an outdated version of the Internet browser. You can get Mozilla to work only by updating the corresponding utility.

Important: You only need to download installation files from the official Mozilla Firefox page. This technique will save you from many problems and failures in the future.

No messages

Does Firefox take a long time to start? This often happens when the processor is busy. Once you shut down a few background programs, your computer will start working faster. And the browser too.

Unfortunately, it increasingly happens that a user opens Firefox, but sees nothing in response - no error messages, no utility crashes, or any other system responses.

How to proceed? Can:

1. Reinstall the browser, first removing it from the computer completely.
2. Restore the system. To do this, you need to open "Start" - "All Programs" - "Accessories" - "System Tools" - "Recovery", and then follow the instructions on the screen.
3. Disable antivirus and other OS protection tools.
4. Launch Firefox in safe mode. To do this, press Shift and double-click on the browser shortcut.

That's all. Firefox won't start? We got acquainted with the most common mistakes and ways to solve them.

Does the Firefox browser console launch when you activate your browser? You need to click on the cross in the corresponding window. To re-launch the console, just hold down Ctrl + Shift + I.

One of the most common problems with any browser is when web pages refuse to load. Today we will take a closer look at the reasons and ways to solve the problem when the Mozilla Firefox browser does not load pages.

The inability to load web pages in the Mozilla Firefox browser is a common problem that can be affected by various factors. Below we will look at the most common ones.

Reason 1: no internet connection

The most common, but also common reason that Mozilla Firefox does not load pages.

First of all, you will need to make sure that your computer has an active internet connection. You can check this by trying to launch any other browser installed on your computer, and then going to any page in it.

In addition, you should check whether another program installed on the computer is taking up all the speed, for example, any torrent client that is currently downloading files to the computer.

Reason 2: Firefox is blocked by antivirus

A slightly different reason, which may be related to the antivirus installed on your computer, which may be blocking access to the Mozilla Firefox network.

To rule out or confirm this possibility of a problem, you will need to temporarily pause your antivirus and then check if pages load in Mozilla Firefox. If, as a result of performing these steps, the browser’s operation has improved, then you will need to disable network scanning in your antivirus, which, as a rule, provokes such a problem.

Reason 3: changed connection settings

Firefox may not be able to load web pages if the browser has connected to a proxy server that is not currently responding. To check this, click on the browser menu button in the upper right corner. In the menu that appears, go to the section "Settings" .

"Additional" and in the subtab "Net" in the block "Compound" click the button "Tune" .

Make sure you have the checkbox next to "No proxy" . If necessary, make the necessary changes and then save the settings.

Reason 4: add-ons do not work correctly

Some add-ons, especially those that change your real IP address, may cause Mozilla Firefox to not load pages. In this case, the only solution is to disable or remove the add-ons that caused the problem.

To do this, click on the browser menu button, and then go to the section "Extras" .

In the left area of ​​the window, go to the tab "Extensions" . A list of extensions installed in the browser will be displayed on the screen. Disable or remove as many add-ons as possible by clicking the corresponding button to the right of each one.

Reason 5: "DNS Prefetch" function is activated

Mozilla Firefox has this feature enabled by default. "DNS Prefetch" , which is aimed at speeding up the loading of web pages, but in some cases it can lead to crashes in the web browser.

To disable this feature, follow the link in the address bar about:config , and then in the window that appears, click on the button “I take the risk!” .

A window with hidden settings will appear on the screen, in which you will need to right-click in any free area from the parameters and go to the item in the context menu that appears “Create” – “Boolean” .

In the window that opens, you will need to enter a name for the setting. Write the following:

network.dns.disablePrefetch

Find the parameter you created and make sure it has a value set to "true" . If you see the value "false" , double-click on the parameter to change the value. Close the hidden settings window.

Reason 6: overabundance of accumulated information

As the browser operates, Mozilla Firefox accumulates information such as cache, cookies, and browsing history. Over time, if you don't pay enough attention to cleaning your browser, you may experience problems loading web pages.

Reason 7: Browser not working correctly

If none of the methods described above helped you, you may suspect that your browser is not working properly, which means the solution in this case is to reinstall Firefox.

First of all, you will need to completely remove the browser from your computer without leaving a single Firefox-related file on your computer.

And after the browser removal is complete, you will need to restart your computer and then proceed to download a fresh distribution, which you will subsequently need to run in order to install Firefox on your computer.

In absolutely any program, even the most ideal one, sometimes failures occur. They may be associated with various reasons. And Mozilla is no exception to the rule. It can also experience interruptions, errors and bugs. Users are constantly tormented by the question - “So how to fix these errors?” We will try to answer this as clearly and clearly as possible.

We will look at the most common errors that the system throws when the browser crashes. And if Mozilla Firefox does not work, then you need to very carefully study what kind of error is thrown in order to remove it.

Does not work or does not start Mozilla: What to do?

We will try to help resolve your problem so it never comes back. But first you need to understand why it happens. So let's look at the most common Mozilla errors.

When I click on the shortcut, the browser does not open

It is difficult to explain why this happens, that previously Firefox opened normally and without any problems, but at some point it stopped responding and did not start at all. The cause may be damaged files, viruses, or even system failures.

Let's try to fix this problem:

Option 1. Try restarting your computer. In some cases, this helps and performance is restored. If you have already tried this option and it did not work, follow the following instructions.

Option 2. You can try to roll back the data to an earlier version (this option is available on Windows 7 and later versions). In most cases, this turns out to be effective and helps with such an error. How to do it:

• Select a restore point and carry out this operation.
• After the data has been rolled back, restart your computer and try logging into Firefox again.

Option 3. The antivirus is blocking the browser. Try disabling your security system for a while and launching your browser. If it starts, then you will need to disable the network scanning system for Mozilla to work normally. But be aware that this may increase the risk of your computer becoming infected with malware.

Option 4. You should try opening Firefox in safe mode. And if the browser starts normally in it, then the problem is some installed extensions and add-ons. In this case, while in this mode, try disabling all extensions and plugins. And if later you start in normal mode without any problems, then simply find and remove the extension that prevents the program from starting.

Browser is not responding

Probably the most common error that users may encounter. Very often it may happen that when using a program, it suddenly freezes and does not respond to anything, and in the browser title it writes: “Not responding.” Let's figure out how to fix this error.

The task manager will help us here:

Of course, all data will be lost and the tabs will be closed, but they can be restored by clicking the restore button that appears in the browser during emergency program closures.

IfFirefox still doesn't respond:

This may mean that there are certain problems with access rights to the program.

Now try opening your browser again, it should work. If not, then only a complete reinstallation will help.

Very slow when working

A similar problem occurs in several cases. Poor computer specifications, system overload, a lot of garbage in the form of history, cookies and cache, as well as malware.

1. In the first case, everything is clear. You need to either acquire a more powerful computer, or minimize the amount of RAM and processor memory consumed by reducing running processes. In simple words, just remove all unnecessary and almost unnecessary programs that take up too much RAM memory.
2. In the second case, the Mozilla browser may glitch if you have too many tabs and different programs running. Moreover, this can happen even on a computer stuffed with cool components. What to do in this case:

— Close all programs that consume a lot of RAM.

— Free up more memory by removing some unnecessary processes.

- Clean the registry and temporary files using CCleaner.

1. The reason may also be a large amount of garbage that has accumulated over the entire time you have been working in a web browser. Then you need to do the following:

Well, the problem with viruses is solved, I think it’s clear how. Install any antivirus (if it is not already installed). Run a scan of your entire computer for viruses. And if, upon completion of the scan, the program detects them, delete them. After which you need to restart the system and you can try to launch the browser.

Profile error in Mozilla Firefox

As a rule, such an error indicates that the profile in the browser has been damaged, moved, or completely deleted. You can try to restore the data, but it will be easier to create a new profile.

How to do it:

The most universal way is to reinstall;)

If you have tried everything listed above, but your problem has not been solved, or you have a completely different error for which you did not find a solution in this article, then in this case the ideal option would be to completely reinstall the Mozilla Firefox program. Read the article -. The whole process and all the subtleties of removing and installing the browser are described in detail there.