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Outlook not working completely in Firefox

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  • Last reply by cor-el

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Just today (2-13-24) I discovered that certain functions of Outlook (web based) do not work in Firefox. All functions do work in Edge browser. Windows 10, Home version. I can read my emails but cannot delete them. I also cannot delete Junk Email and probably others, but I've not attempted others. When I try to delete Junk emails, it seems that they are deleted, as they disappear temporarily from the folder, only to reappear after leaving the Junk folder and returning to it.

Looking for possible solutions.

Just today (2-13-24) I discovered that certain functions of Outlook (web based) do not work in Firefox. All functions do work in Edge browser. Windows 10, Home version. I can read my emails but cannot delete them. I also cannot delete Junk Email and probably others, but I've not attempted others. When I try to delete Junk emails, it seems that they are deleted, as they disappear temporarily from the folder, only to reappear after leaving the Junk folder and returning to it. Looking for possible solutions.

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If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block content (Adblock Plus, NoScript, DuckDuckGo PE, Disconnect, Ghostery, Privacy Badger, uBlock Origin), always make sure such extensions do not block content.


You can try these steps in case of issues with webpages:

You can reload webpage(s) and bypass the cache to refresh possibly outdated or corrupted files.

  • hold down the Shift key and left-click the Reload button
  • press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
  • press "Command + Shift + R" (Mac)

Clear the Cache and remove the Cookies for websites that cause problems via the "3-bar" Firefox menu button (Settings), click the padlock icon (Clear cookies and site data) for the domain in the selected tab.

"Remove the Cookies" for websites that cause problems:

  • Settings -> Privacy & Security
    Cookies and Site Data: "Manage Data"

"Clear the Cache":

  • Settings -> Privacy & Security
    Cookies and Site Data -> Clear Data -> [X] Cached Web Content -> Clear

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or if userChrome.css/userContent.css is causing the problem.

  • switch to the Default System theme: "3-bar" menu button or Tools -> Add-ons -> Themes
  • do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

You can check for issues with Enhanced Tracking Protection. Firefox shows a purple shield instead of a gray shield at the left end of the location/address bar in case Enhanced Tracking Protection is blocking content.

  • click the shield icon for more detail and possibly disable the protection

You can check the Web Console for relevant-looking messages like blocked content.