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Reverting to a specific version of Firefox browser?

  • 6 replies
  • 1 has this problem
  • 21 views
  • Last reply by cor-el

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The last fully compatible version I could use was 78.6.1 ESR. I know I need a new profile to go backwards but I can't find the specific file. I can see the version I would like in a directory but don't know how to download/install it. Thank you all:)

Have 2011 Mac which won't support newer OS updates.

The last fully compatible version I could use was 78.6.1 ESR. I know I need a new profile to go backwards but I can't find the specific file. I can see the version I would like in a directory but don't know how to download/install it. Thank you all:) Have 2011 Mac which won't support newer OS updates.

All Replies (6)

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What is the problem with the current Firefox 78.9.0esr release on your Mac?

https://www.mozilla.org/firefox/78.9.0/system-requirements/

I don't know whether this article works for the ESR series: Install an older version of Firefox.

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Can't access regularly used websites like my bank, health insurer etc. Says "unsupported browser" - can't upgrade my OS which is the obvious fix. Want to go back a couple of updates to the point where everything was working. Don't want to use another browser. Have read the articles about downgrading Firefox but can't find a link to a specific version of Firefox and don't want to go all the way back to 77 ESR which is where I'm being pointed. Would like to reset or re-installing Firefox as of 78.6.1 ESR

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The problem is that the version number is too old, so going back will definitely not improve the problem: regardless of the point version in the series, Firefox 78 ESR identifies as Firefox 78.0.

Do you want to try lying to the site? What I mean is, tell sites you run Firefox 87.0 this way:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

(2) In the search box in the page, type or paste general.useragent.override and pause while the list is filtered

Assuming you see a bar with Boolean Number String:

(3) Click String then click the + button to create the new preference.

(4) Paste the following into the blank field and then click the blue check mark button to save the change:

Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:87.0) Gecko/20100101 Firefox/87.0

An example screenshot is attached, showing the saved preference and how sites see the lie.

If you saw an existing preference in Step 2, double-click it to update the user agent string.

This is global setting, so possibly some sites will not work properly if they track differences between Firefox versions. In that case, you either can double-click and edit 87 back to 78 in both places, or click the trash can at the right end of the bar to delete the preference.

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Your "disguise" solution seems like a viable alternative but I'm a neophyte and a little concerned about creating a bigger problem. I appreciate that your area of expertise is Mozilla but with my legacy Mac (see below) do you know if I can upgrade the OS before I try your solution? Currently running ancient El Capitan and I added memory to 16GB. When I check for updates it doesn't offer any?

 Model Name:	MacBook Pro
 Model Identifier:	MacBookPro8,2
 Processor Name:	Intel Core i7
 Processor Speed:	2 GHz
 Number of Processors:	1
 Total Number of Cores:	4
 L2 Cache (per Core):	256 KB
 L3 Cache:	6 MB
 Memory:	16 GB
 Boot ROM Version:	MBP81.0050.B00
 SMC Version (system):	1.69f4
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Hmm, best not to take my advice on MacOS stuff. Here's the Wikipedia page on 10.12 for reference in case it helps.

https://en.wikipedia.org/wiki/MacOS_Sierra

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Websites regularly update their code (usually JavaScript) and that can cause older browser versions to stop working properly, so if it worked before with Firefox 78 and it stopped recently then it is likely that the JavaScript used by this website isn't compatible with Firefox 78. You can check their FAQ pages to see what browsers they support. Going back to an older Firefox version (before 78) will only make things worse.