What's your computer system and Firefox version?

You may have a corrupt profiles.ini file. Close Firefox. Open your file browser to this hidden location:

• Mac: *~/Library/Application Support/Firefox/
• Linux: *~/.mozilla/firefox/
• Windows: %AppData%\Mozilla\Firefox\
• *C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\

Locate the profiles.ini file. Then rename or delete it. Use this new profile as is. Is the problem still there?

There might be a problem with permissions/ownership of involved folders/files preventing access. You can check for problems with the profiles.ini file that registers profiles.

See:

• https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

You can try these steps:

• use the Profile Manager to create a new profile
  https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• register an orphaned profile that isn't listed in the Profile Manager

You can find the profiles.ini file in this hidden location:

• Windows: %AppData%\Mozilla\Firefox\
  C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\

You can recover an orphaned profile via these steps:

• use the Profile Manager to create a new profile
  https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• click "Choose Folder" in the Profile Manager
• browse to the location of this profile to register this profile in the Profile Manager and use this profile

See "Profile was moved or renamed":

• https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

Note that you should never use "Choose Folder" to specify a folder that already contains files that do not belong to Firefox. Only use "Choose Folder" to recover an profile that isn't listed in the Profile Manager.

• http://kb.mozillazine.org/profiles.ini_file
• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Profile_folder_-_Firefox

FredMcD said

What's your computer system and Firefox version? You may have a corrupt profiles.ini file. Close Firefox. Open your file browser to this hidden location:

• Mac: *~/Library/Application Support/Firefox/
• Linux: *~/.mozilla/firefox/
• Windows: %AppData%\Mozilla\Firefox\
• *C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\

Locate the profiles.ini file. Then rename or delete it. Use this new profile as is. Is the problem still there?

FredMcD said

What's your computer system and Firefox version? You may have a corrupt profiles.ini file. Close Firefox. Open your file browser to this hidden location:

• Mac: *~/Library/Application Support/Firefox/
• Linux: *~/.mozilla/firefox/
• Windows: %AppData%\Mozilla\Firefox\
• *C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\

Locate the profiles.ini file. Then rename or delete it. Use this new profile as is. Is the problem still there?

I can't close Firefox, it appears it never completely installed before the "profile" message box came up. I've never installed Firefox on this pc, why would there be a Firefox profile at all??

Could you tweak two Windows settings first:

(A) Set Windows to show hidden files and folders

https://support.microsoft.com/en-us/help/14201/windows-show-hidden-files

(B) Set Windows to show all file extensions

https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

Then explore to the Firefox data folder:

C:\Users\your-user-name\AppData\Roaming\Mozilla\Firefox

In this folder you should find the following (possibly more):

(1) Folder named Profiles

(2) File named Profiles.ini

The error message you got is nearly always caused by Firefox not being able to find a profile folder under Profiles that is listed in the Profiles.ini file.

You can view Profiles.ini in Notepad to see what Firefox is looking for (right-click the file, then click Edit). For example (the first part of the profile folder name is randomized):

[Profile0]
Name=default
IsRelative=1
Path=Profiles/4M2wJB.default

Then you can double-click into the Profiles folder to see whether the expected folder (in this example, 4M2wJB.default) is missing.

If it's not missing, perhaps something is wrong with its permissions, as mentioned by cor-el, or its contents.

FredMcD said

What's your computer system and Firefox version? You may have a corrupt profiles.ini file. Close Firefox. Open your file browser to this hidden location:

• Mac: *~/Library/Application Support/Firefox/
• Linux: *~/.mozilla/firefox/
• Windows: %AppData%\Mozilla\Firefox\
• *C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\

Locate the profiles.ini file. Then rename or delete it. Use this new profile as is. Is the problem still there?

I don't have Firefox, I'm trying to install it for the first time on a new computer. Why would I have a Firefox profile in that case?

cor-el said

There might be a problem with permissions/ownership of involved folders/files preventing access. You can check for problems with the profiles.ini file that registers profiles. See:

• https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

---

You can try these steps:

• use the Profile Manager to create a new profile
  https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• register an orphaned profile that isn't listed in the Profile Manager

You can find the profiles.ini file in this hidden location:

• Windows: %AppData%\Mozilla\Firefox\
  C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\

You can recover an orphaned profile via these steps:

• use the Profile Manager to create a new profile
  https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• click "Choose Folder" in the Profile Manager
• browse to the location of this profile to register this profile in the Profile Manager and use this profile

See "Profile was moved or renamed":

• https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

Note that you should never use "Choose Folder" to specify a folder that already contains files that do not belong to Firefox. Only use "Choose Folder" to recover an profile that isn't listed in the Profile Manager.

---

• http://kb.mozillazine.org/profiles.ini_file
• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Profile_folder_-_Firefox

I don't have Firefox, I'm trying to install it on a new computer. Why would I have a pre-existing Firefox profile in that case? Shouldn't it be part of the install process for a first time install?

Hi wenrob35, Firefox creates the profile as part of the installation. Or at least, that is what is supposed to happen. What is unclear is why you get the error: did profile creation fail due to something about the installer? Is Windows denying access? Did security software interfere? Please see my earlier reply about what folder Firefox looks in.

jscher2000 said

Hi wenrob35, Firefox creates the profile as part of the installation. Or at least, that is what is supposed to happen. What is unclear is why you get the error: did profile creation fail due to something about the installer? Is Windows denying access? Did security software interfere? Please see my earlier reply about what folder Firefox looks in.

Hi Jscher2000 and thanks for the speedy reply, and I'm still confused. The questions you pose here seem relevant, but your earlier reply still spoke about looking for an existing profile folder. What am I missing? Sorry if I'm asking basic questions, this is beyond my experience.

Hi wenrob35, if you follow the navigation steps in my earlier reply, do you find the expected Firefox folder and Profiles.ini file? If they are missing, you could try re-running the installer.

If you find those, then do you find the profile folder that matches what is listed in the Profiles.ini file?

No, I didn't do that before because I couldn't get past the idea that there shouldn't be a Firefox profile existing on my computer. But I just did it now. There is a Firefox folder and the profiles.ini file (below). I think you're saying that within the Firefox folder there should be a file called QcGURZkQ.default, right? OK, there isn't. Where do I go from there? Thanks very much for your help on this.

[General] StartWithLastProfile=1

[Profile0] Name=default IsRelative=1 Path=Profiles/QcGURZkQ.default

Try deleting the Profiles.ini file. At startup, Firefox should either create or offer to create a profile folder. Or if Firefox seems helpless, you can use the steps in this article: Profile Manager - Create, remove or switch Firefox profiles.

wenrob35 said

I think you're saying that within the Firefox folder there should be a file called QcGURZkQ.default, right?

Path=Profiles/QcGURZkQ.default

It should be inside the Profiles folder:

Firefox\Profiles\QcGURZkQ.default

Boot the computer in Windows Safe mode with network support to see if that has effect in case security software is causing problems.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

jscher2000 said

Try deleting the Profiles.ini file. At startup, Firefox should either create or offer to create a profile folder. Or if Firefox seems helpless, you can use the steps in this article: Profile Manager - Create, remove or switch Firefox profiles.

Hey, that worked!! Thanks very much. At last!

That is what we have been telling you to do since day one.

I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution more easily.

Thank you for contacting Mozilla Support.

Sorry, it was unclear to me. The way jscher2000 explained it in the back and forth made more sense. Anyhow, thanks for trying to help - I'm impressed with this community support. And now I have Firefox on my computer. Yay!