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Firefox version that will work with osx 10.11.6 before

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I updated Firefox and overrode the working version I was using. The new version error message is: Requires osx 10.12 or later. I cannot upgrade my Mac operating systems. It’s and old MacBook Pro I cannot access the internet. Safari does not work on my computer. I need your help! Call Mike at 7813213124. My operating system is 10.11.6 and I cannot upgrade. Please help

I updated Firefox and overrode the working version I was using. The new version error message is: Requires osx 10.12 or later. I cannot upgrade my Mac operating systems. It’s and old MacBook Pro I cannot access the internet. Safari does not work on my computer. I need your help! Call Mike at 7813213124. My operating system is 10.11.6 and I cannot upgrade. Please help

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The last release of Firefox for your OS version was 78.15.0esr (ESR stands for Extended Support Release, Firefox Mac OS X 10.9, 10.10 and 10.11 users move to Extended Support Release).

You can download from here:

https://archive.mozilla.org/pub/firefox/releases/78.15.0esr/mac/en-US/

If you prefer a locale/language other than U.S. English, click the .. link on that page to move up to the directory of different locales/languages and then click into the desired one.

After downloading the file, use the steps here: How to download and install Firefox on Mac.

Success?

I assume the later version of Firefox never ran, so it didn't make your data files incompatible with the older release. However, if it did, then reversing that would involve other steps.

Note: this forum does not accept email replies, so please follow up in this thread at https://support.mozilla.org/questions/1419495.