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XML Parsing Error: Firefox Opens But Doesn't Work

  • 4 replies
  • 2 have this problem
  • 562 views
  • Last reply by leadwap01

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So some days ago my firefox browser ran an automatic update and afterwards, it returned this error message:

"XML Parsing Error: undefined entity Location: chrome://browser/content/browser.xhtml Line Number 46, Column 1: " I'm being hesitant with uninstalling it cos I have some important passwords and accounts logged into it. Please, I need help with this.

So some days ago my firefox browser ran an automatic update and afterwards, it returned this error message: "XML Parsing Error: undefined entity Location: chrome://browser/content/browser.xhtml Line Number 46, Column 1: <html id="main-window">" I'm being hesitant with uninstalling it cos I have some important passwords and accounts logged into it. Please, I need help with this.
Attached screenshots

Chosen solution

Do a clean reinstall of the current Firefox release and delete the Firefox program folder before installing a fresh copy of the current Firefox release.

If possible uninstall your current Firefox version to cleanup the Windows Registry and settings in security software.

  • do NOT remove "personal data" when you uninstall the current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including personal data in profiles created by other Firefox versions

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

  • (64-bit Firefox) "C:\Program Files\Mozilla Firefox\"
  • (32-bit Firefox) "C:\Program Files (x86)\Mozilla Firefox\"
  • it is important to delete the Firefox program folder to remove all the files and make sure there are no problems with files that were leftover after uninstalling

Your personal data like bookmarks is stored in the Firefox profile folder, so you won't lose personal data when you reinstall or update Firefox, but make sure NOT to remove personal data when you uninstall Firefox as that will remove all Firefox profile folders and you lose your personal data.

If you keep having problems then you can create a new profile as a quick test to see if your current profile is causing the problem.


Reinstall Firefox

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All Replies (4)

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Hi leadwap01,

Can you reproduce in Firefox safe mode?

SEE: Diagnose Firefox issues using Troubleshoot Mode

It may be a addon or hardware acceleration affecting this (making the error show up).

Hope it helps. Thank You.

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Thank You for your response Shekhar, but the browser doesn't even load up for me to able to access the menu.

This simply means that it's not possible to run the safe mode.

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Chosen Solution

Do a clean reinstall of the current Firefox release and delete the Firefox program folder before installing a fresh copy of the current Firefox release.

If possible uninstall your current Firefox version to cleanup the Windows Registry and settings in security software.

  • do NOT remove "personal data" when you uninstall the current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including personal data in profiles created by other Firefox versions

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

  • (64-bit Firefox) "C:\Program Files\Mozilla Firefox\"
  • (32-bit Firefox) "C:\Program Files (x86)\Mozilla Firefox\"
  • it is important to delete the Firefox program folder to remove all the files and make sure there are no problems with files that were leftover after uninstalling

Your personal data like bookmarks is stored in the Firefox profile folder, so you won't lose personal data when you reinstall or update Firefox, but make sure NOT to remove personal data when you uninstall Firefox as that will remove all Firefox profile folders and you lose your personal data.

If you keep having problems then you can create a new profile as a quick test to see if your current profile is causing the problem.


Reinstall Firefox

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Thank You so much. The issue is fixed after I followed your instructions.

Thank You.