First, could you exit Firefox and test starting up with just the program name? The purpose is to bypass any shenanigans in the shortcut you're using. Type or paste the following in the Windows 10 search box or in the Windows Run dialog (Windows key + R), then press Enter to execute it:

firefox.exe

Same problem?

If that bypasses the problem, check your shortcut using the steps in the next post.

Firefox usually gives this error looking for the default profile path specified in the profiles.ini file. You can inspect that file's contents. It sounds as though you are already familiar with the location, but just in case, either:

(1) Navigate "up" from your current profile folder

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

In the Windows Explorer address bar, click the word Firefox, or if you have an up-arrow icon to move up in the folder hierarchy, click that twice, or expand the folder hierarchy in the tree view pane on the left side and click Firefox.

(2) Launch Windows Explorer using a shortcut

Type or paste the following in the Windows 10 search box or in the Windows Run dialog (Windows key + R), then press Enter to load it:

%APPDATA%\Mozilla\Firefox

Once you are viewing the Firefox folder:

By default, Windows hides the .ini extension. You may want to change that now. See: https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

You can open profiles.ini in Notepad or Wordpad or another text editor. If you have multiple profiles, look for the one which has

Default=1

That's the one Firefox is not able to find. Is that the one you want to use? If not, you can edit the Path to match the real folder name.

Over in Windows Explorer, double-click in the Profiles folder to more easily copy/paste it. You can right-click > Rename on the folder name, make sure all of it is selected (Windows may stop at the dot), then press Ctrl+c to copy. Click away or press Esc to cancel the renaming.

Back in profiles.ini, delete the part of the path after Profiles/ and paste the true name there. Make sure when you save that the file's format is not changed from plain text to anything else. Then when you start Firefox, it should look for and hopefully find the real folder.

Success?

If starting Firefox from the search box or Run dialog gives you a "clean" launch, your desktop shortcut might be hacked. Here's how you can check that:

• Desktop shortcut: right-click the icon, choose Properties
• Pinned taskbar icon: right-click the icon, right-click Mozilla Firefox, choose Properties

Windows normally will select the Shortcut tab. If not, go ahead and click the Shortcut tab.

The Target line should not have anything after this part:

• 32-bit Firefox on 64-bit Windows: "C:\Program Files (x86)\Mozilla Firefox\firefox.exe"
• Otherwise: "C:\Program Files\Mozilla Firefox\firefox.exe"

If anything is listed after that, clear it out and save your change. To test, you can either:

• Desktop shortcut: double-click the icon to launch a new window
• Pinned taskbar icon: right-click the icon, click Mozilla Firefox to launch a new window

If you get a normal startup or a new window showing your home page, the shortcut is back to normal.

One other thing:

Firefox 55.0-55.0.2 had problems with special characters in the profile path, particularly in the Windows username. This was reported with the apostrophe, e.g., O'Reilly, and also with some accented characters. It was supposed to be fixed in Firefox 55.0.3, but perhaps they missed something.

Does your username or (non-working) profile name have any characters that are not basic letters and numbers?

jscher2000, the one I want to use is the one with "Default=1". I've tried copying the information to a new profile, but the new profile doesn't show the bookmarks either.

To add to the confusion, my home page now works but nothing else does.

Do you have any compressed .jsonlz4 backups in the bookmarkbackups folder that you can restore?

The name of a JSON bookmarks backup file includes a total item count (folders and separators included) and an hash value to prevent saving the same backup more than once.

• bookmarks-YYYY-MM-DD_<item count>_<hash>.jsonlz4.

If the Places Maintenance extension can't repair the places.sqlite database then remove all places.sqlite file(s) in the Firefox profile folder to make Firefox rebuild the places.sqlite database from the most recent JSON backup in the bookmarkbackups folder.

• keep a backup copy of places.sqlite in case a new places.sqlite database has to be created
• http://kb.mozillazine.org/Unable_to_process_the_backup_file_-_Firefox

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

I have bookmark backups, but they are not working. When I hit restore, I get an "unable to process backup file" error.

If the Places Maintenance extension can't repair the places.sqlite database then remove all places.sqlite file(s) in the Firefox profile folder to make Firefox rebuild the places.sqlite database from the most recent JSON backup in the bookmarkbackups folder.

• keep a backup copy of places.sqlite in case a new places.sqlite database has to be created
• http://kb.mozillazine.org/Unable_to_process_the_backup_file_-_Firefox

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

I tried that and Firefox still can't read the back-up files.

Anyone have any ideas on how to fix this?

Could you decompress the file and take a quick look at it to see whether it seems to have sensible data in it? The easiest way is to use a script snippet in Firefox's Browser Console.

(A) Preparation Steps

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste devt and pause while the list is filtered

(3) Double-click the devtools.chrome.enabled preference to switch the value from false to true

(B) Run script

(1) Open

https://gist.github.com/jscher2000/4403507e33df0918289619edb83f8193

and click the "Raw" button to the upper right of the script code window to display it on a stand-alone page.

(2) Select and copy the entire script

(3) Open the Browser Console using either Ctrl+Shift+j or menu > Developer > Browser Console

(4) In the command line slot at the bottom, paste the script and press Enter to run it

(5) That should pop up a file browser window showing your profile folder. Double-click bookmarkbackups and double-click a file you want to decompress.

(6) OK the option to view the decompressed filed in a tab.

Firefox 55 normally will read in the raw text of the file then try to lay it out using a structured viewer with various expandable sections. Does that work?

I used your page to test the most recent set of bookmarks and it has valid coding according to the page and when exported as HTML works fine. Firefox itself still won't recognize the file.

Hi Dragonmage650, this afternoon I read about a bug that will be fixed in Firefox 58 which occurs when a date field has a 0 date. The Export to HTML script will now replace a blank or 0 date with today's date. Could you try it again? Please bypass cache using Ctrl+Shift+r to make sure you get the 11/17/2017 version.

Still doesn't work. I'm also getting a "The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem" error on my new install of Firefox.

Firefox is not producing a new places.sqlite file when I open it.

Dragonmage650 said

I'm also getting a "The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem" error on my new install of Firefox.

Firefox is not producing a new places.sqlite file when I open it.

Sounds as though you have already found this article: Fix "The bookmarks and history system will not be functional" error message.

Why is Firefox not creating a new places.sqlite file? Are you using automatic private browsing mode? You can check for that on the Options page, Privacy & Security panel. Either of these will invoke automatic private browsing:

• Firefox will: Never remember history
• Firefox will: Use custom settings for history PLUS "Always use private browsing mode" has a check mark in the box

If you have either of those settings, please turn off the feature and see whether Firefox can create places.sqlite on the next startup.

Otherwise, I wonder whether it would make sense to create a new profile and selectively move data to it. If you want to test that possibility:

New Profile Test

This takes about 3 minutes, plus the time to test the places system.

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

Click the Create a New Profile button, then click Next. Assign a name like Nov2017, ignore the option to relocate the profile folder, and click the Finish button.

After creating the profile, scroll down to it and click the Set as default profile button below that profile, then scroll back up and click the Restart normally button. (There are some other buttons, but please ignore them.)

Firefox should exit and then start up using the new profile, which will just look brand new. For the time being, skip over any tabs asking about enabling extensions.

Do bookmarks work any better in the new profile?

When you are done with the experiment, open the about:profiles page again, click the Set as default profile button for your normal profile, then click the Restart normally button to get back to it.

I do not have automatic private browsing turned on.

The new profile works and bookmarks normally, but the old one still gives me the same "The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem" error.

Do you want to try copying the "working" places.sqlite database from your new profile to your regular profile? I think this is how you would do that:

Let's assume you are running Firefox in your regular profile.

Open your Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then check for any of these files and, if you find them, remove them:

• places.sqlite
• places.sqlite-shm
• places.sqlite-wal

In the Windows Explorer address bar, Firefox lets you click on the word Profiles to move up a level to that folder. Then you can double-click into the other profile folder.

Right-click places.sqlite > Copy

Then go Back twice to return to your regular profile, right-click a blank area of the folder > Paste.

Start Firefox back up again. Any improvement?

Oops, I forgot the last step, which is if it works, restore a bookmark backup: Restore bookmarks from backup or move them to another computer

The new profile worked for a little while, but after I shut my computer down and restarted I get the same "The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem" error as with the default profile.

Dragonmage650 said

The new profile worked for a little while, but after I shut my computer down and restarted I get the same "The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem" error as with the default profile.

This occurred after you restarted Windows, hmm. If you use the about:profiles screen to switch back to your old profile, is that one still affected, too?

Microsoft has a utility to show you what runs at startup, in case there is anything unnecessary or suspicious. The tool also has numerous other tabs, but I think Logon would be the most relevant.

https://docs.microsoft.com/en-us/sysinternals/downloads/autoruns

Old profile is still affected. I'm wondering if it might be something with windows security essentials because sometimes I get an error message from that.