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Why does Firefox want to restart in 32-bit mode, on some sites sometimes and sometimes not. ie. Hotmail


There are times when I log into some sites, and it won't complete and Firefox is telling me that I need to restart in 32-bit mode to view the site. Does this mean I have to switch my Mac from 64-bit back to 32-bit? Also, why do some sites tell you Firefox needs to restart in 32-bit mode, but only sometimes. Like Hotmail. Sometimes when I log in, I get that message, sometimes I don't. Is this an issue with Firefox or the site?

Additional System Details

Sites Affected


Installed Plug-ins

  • RealPlayer Plugin
  • The Flip4Mac WMV Plugin allows you to view Windows Media content using QuickTime.
  • Office Live Update v1.0
  • DivX Web Player version
  • iPhoto6
  • 4.0.50524.0
  • Microsoft Office for Mac SharePoint Browser Plug-in
  • Shockwave Flash 10.1 r102
  • Speed Download Plugin. Allows downloads to be redirected to Speed Download
  • Java Plug-In 2 for NPAPI Browsers
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in web pages. For more information, visit the QuickTime Web site.


  • User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0) Gecko/20100101 Firefox/4.0

More Information

fredhanke 0 solutions 1 answers

Add my name to this problem. I have OS X 10.6. Please fix it!!!

Question owner

Kills me that after a month of posting my question, your the only one that's replied...but with the same issue. Does Firefox NOT check their support pages?

Question owner

By the way, still having those issues.

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Helpful Reply

On a Mac, Firefox 4 is a 64 bit application.

Not all plugins support 64 bit and if not then you need to start Firefox in 32 bit mode to use that plugin.

  1. Close Firefox
  2. Open the Applications folder in Finder
  3. Right click or control-click the Firefox.app icon
  4. Select "Get Info"
  5. Select or Deselect "Open in 32-bit mode"
  6. Close the "Firefox Info" window
  7. Restart Firefox

Question owner

Thanks cor-el, didn't know that's how you switch Firefox to 32-bit mode. That will be very helpful.

I understand about some plugins not being compatible with 64-bit. But in regards to Hotmail (and other sites with similar issues), why would it tell me to start in 32-bit mode at times, and other times it doesn't? Glitch? Tx.

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  • Moderator
10780 solutions 97024 answers

Silverlight ?

Are you uploading attachments ?

Question owner

I do have silverlight installed. You have to if you want to access any MS site. Not uploading attachments. Only happens when I access the sites. But like I said, it happens sometimes, and other times it doesn't. Actually happened yesterday, but before that, hadn't happened in about a couple of weeks. Didn't do anything different.

captaindigital 0 solutions 1 answers

Okay. I followed your instructions and switched Firefox to 32-bit mode. And now I'm stuck there. WTH?! There is no apparent way to get back to 64-bit mode. What do I do now?

Backhome77 0 solutions 1 answers

I have the same problem. Only in Hotmail, and only at certain times, like trying to save a draft. It's really annoying. I might expect Firefox to have compatibility issues with some smaller websites, but not something like Hotmail.