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Why won't Firefox 12.0 won't open/load .aspx pages?


When I am on ancestry.com and researching various genealogy family members. If I right click an ancestor and do "open in new window," instead of opening in Firefox 12.0 (which is set as my default browser) it opens in IE. If I click on the properties of the item(s) I'm opening to see what they are, they say they are ASPX files. Obviously the URL can be opened in Firefox after it's been opened in IE, but not directly with a right-click from Ancestry.com. Why is that? (Note, you may need to be a ancestry.com member to see the info displayed within this URL.)

Additional System Details

Sites Affected


Installed Plug-ins

2007 Microsoft Office System, Active Touch General Plugin Container, Adobe Acrobat (I seem to have two and, Ancestry.com Image Viewer Plugin, Coupons Inc Coupon Printer Manager, Google Earth Plugin, Google Update, Homestead SiteBuilder Plugin for Mozilla, Hulu for Desktop, Java Deployment Toolkit, Java Platform, Logmein, Microsoft Office Live, Quicktime Plugin, Shockwave Flash (I have two), Shockwave for Director, Silverlight Plugin, Windows Live Photo Gallery, Yahoo ActiveX Plugin Bridge


  • User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0) Gecko/20100101 Firefox/12.0

More Information

Checked to make sure Firefox is my default browser (it is). Tried to find a way to see if there is a default for opening .aspx URLs (could not)

  • Top 10 Contributor
2360 solutions 20906 answers

If you use the add-on IE Tab or one of its derivatives, can you check whether there is an option that controls this?

If you just left-click or if you Ctrl+click (open in new tab), do those work normally or do those also launch an IE window?

The .aspx extension can be used to delivery ordinary web pages, PDFs, or any other kind of file. Firefox generally looks at the content-type sent by the server. Firefox compares the content-type with the list of application handlers to determine how to open it.

The content-type is invisible in ordinary browsing. You can view it using an add-on, or perhaps more quickly if you use Rex Swain's HTTP viewer tool. After you a logged in to Ancestry, paste the URL into the form on http://www.rexswain.com/httpview.html and click the bubble for HEAD then click Submit. On the results page, if you scroll down a bit to the "Receiving Header" section, what Content-Type is listed there?

With that information, we may be able to find a problem entry here:

orange Firefox button or classic Tools menu > Options > Applications