So what is XULRunner? It is a run time environment developed by Mozilla to provide a common back-end for XUL applications designed for Firefox. Some XUL Applications are Songbird music player, Elixon WCMS/XUL etc.
How to Fix XULRunner Error
In order to fix the XMLRunner Platform version compatibility error, we need to properly uninstall currently installed Firefox and delete the Firefox folder from programs files. After removing remnants of currently installed Firefox browser from our computer, we should download and install latest version of Firefox browser.
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