FIX: File couldn’t be saved because unknown error occurred

Matthew Adams
by Matthew Adams
Windows & Software Expert
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  • Mozilla Firefox is a great privacy-oriented browser with millions of users around the world.
  • Many Firefox users reported File could not be saved because an unknown error occurred message while downloading certain files, but there’s a way to fix it.
  • Are you having additional problems with Firefox? If so, be sure to check our Firefox errors section for more helpful guides.
  • Having a good browser is important, and if you want to learn more about Firefox, head over to our dedicated Firefox Hub.
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The unknown error occurred error is a download issue that occurs in Firefox. Some Firefox users can’t download files or open email attachments when this error message pops up: [file path] could not be saved because an unknown error occurred. Try saving to a different location. Does this error message sound familiar? If so, these are a few resolutions that might fix it.

How can I fix File could not be saved because an unknown error occurred error?

1. Reset the download folder settings via about:config page

  1. Open the Firefox browser.
  2. Enter about:config in the browser‘s URL bar and press Return to open the about:config tab shown directly below.
  3. Then search for these five preferences in about:config: browser.download.downloadDir, browser.download.folderList, browser.download.dir, browser.download.useDownloadDir and browser.download.lastDir.
  4. You can quickly select those preferences by entering ‘browser.download’ within about:config’s search box.
  5. If some of those Firefox preferences are modified, right-click each one and select Reset to restore it to the default status.


2. Select an alternative download folder

  1. Click the Open menu button at the top right of Firefox‘s window.
  2. Click General on the left of the Options tab.
  3. Scroll to Files and Applications as in the shot directly below.
  4. Press the Browse button for the Save files to option.
  5. Choose another download directory, and click the Select Folder button.

3. Switch off Firefox extensions

  1. To disable Firefox extensions, click the Open menu button.
  2. Click Add-ons to open the tab shown directly below.
  3. Click Extensions on the left of the tab.
  4. Then press the extensions’ Disable buttons to switch them off.

4. Disable Firefox download plug-ins

  1. The unknown error occurred issue might be due to download manager plug-ins such as Get Right, WinGet, Download Accelerator Plus and FreshDownload. You can disable those plug-ins by clicking the Open menu button and selecting Add-ons.
  2. Click Plugins to open a list of your Firefox plug-ins as below.
  3. Select Never Activate from the download plug-ins’ drop-down menus to disable them.

5. Temporarily disable anti-virus software

Third-party anti-virus software might be blocking Firefox downloads. So, temporarily disabling anti-virus utilities might help fix this issue.

You can temporarily switch most anti-virus utilities off by right-clicking their system tray icons and selecting a disable or turn off option.

Select to disable the software until you restart Windows, and then download something with Firefox.


6. Reinstall third-party firewalls

This is how you can more thoroughly uninstall a third-party firewall with Advanced Uninstaller PRO.

  1. First, click the Download Now button on this homepage to save the Advanced Uninstaller PRO setup wizard.
  2. Open the saved installer to add Advanced Uninstaller PRO to Windows, and then open the software window shown directly below.
  3. Click General > Uninstall Programs to open the window in the screenshot directly below.
  4. Select your third-party firewall listed on that window.
  5. Press the Uninstall button to open the dialog box shown directly below.
  6. Select the Use leftover scanner option on that dialog box window.
  7. Click Yes to confirm and uninstall the firewall software.
  8. An Application uninstall cleanup window will show you leftovers. Select all the leftover registry entries or files and click Next to delete them.
  9. Thereafter, open the third-party firewall’s installer to reinstall the software.

Disabling anti-virus software might not always be enough if you also have an additional third-party firewall utility. Some Firefox users have found the unknown error occurred issue to be due to Comodo Firewall. As such, reinstalling third-party firewall software is another potential fix.


7. Refresh the Firefox browser to its default settings

  1. To refresh Firefox, input about:support in the browser‘s URL bar and press Enter to open the tab shown directly below.
  2. Press the Refresh Firefox button on that tab.
  3. A Refresh Firefox dialog box window will then open. Click Refresh Firefox on that window to confirm your selected option.

At least one of those fixes will probably resolve the unknown error occurred error so that you can download software and documents in the Firefox browser once again. In addition, opening the browser in Safe Mode might also help fix the error.

We hope that our solutions were helpful to you. If you’re having additional problems, this article also provides further troubleshooting tips for Firefox.

FAQ: Learn more about Firefox

  • Where does Firefox save files?

By default, Firefox saves all your downloaded files in the C:\Users\your_username\Downloads directory.

  • Is Firefox private?

Yes, Firefox is private and it won’t sell your data. However, you’re not private online while using Firefox. If you want to be private online, you need a browser with a VPN such as Opera.

  • Is Firefox better for privacy?

Firefox is open-source and made by a non-profit organization which means that it offers better privacy than other browsers.

  • Is Chrome better than Firefox?

This comes down to personal preference, but in terms of functionality, Chrome offers several features that Firefox doesn’t.

Editor’s Note: This post was originally published in November 2017 and has been since revamped and updated in April 2020 for freshness, accuracy, and comprehensiveness.