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Websites like Gmail and Facebook won't recognize my browser. What's the deal?

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Wash_Jones
Wash_Jones
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It started after a recent Firefox update, I think the one prior to this most recent one. Gmail tells me I'm using a browser it "no longer supports", and redirects me to their basic HTML page. Facebook says I'm using an "Unspported Browser", and I have to log in through the "m.facebook.com" mobile version of the site.

Websites like whatbrowser.com will tell me they don't know what browser I'm using, and other similar sites will tell me they can't detect a user agent string.

I'm pretty sure this has something to do with the various add-ons I have, but I'm not sure. Anyone having similar problems?

It started after a recent Firefox update, I think the one prior to this most recent one. Gmail tells me I'm using a browser it "no longer supports", and redirects me to their basic HTML page. Facebook says I'm using an "Unspported Browser", and I have to log in through the "m.facebook.com" mobile version of the site. Websites like whatbrowser.com will tell me they don't know what browser I'm using, and other similar sites will tell me they can't detect a user agent string. I'm pretty sure this has something to do with the various add-ons I have, but I'm not sure. Anyone having similar problems?

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cor-el
cor-el
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You have some user agent override prefs set to an empty string value, so you do not send a user agent at all.

  1. general.useragent.override:
  2. general.useragent.vendor:
  3. general.useragent.vendorSub:

You can reset all general.useragent prefs via the right-click context menu to the default value to remove them from the about:config page on the next start of Firefox.

See:

I also see that you are in Private Browsing mode (never remember history), but that shouldn't be a problem.