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An error message says an illegal version of Firefox tried to install.

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  • Last reply by cor-el

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An error message says an illegal version of Firefox update tried to install and I should contact my administrator.

An error message says an illegal version of Firefox update tried to install and I should contact my administrator.

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This issue can be caused by the presence of leftover files in the Firefox program folder (defaults\pref) like a file firefox.js that overrides the update URL with a wrong link.

Do a clean reinstall and be sure to remove the Firefox program folder to remove the file(s) that cause the problem.

See: