"Firefox error platform version is not compatible" is an error that may occur due to a failed Firefox update that leaves the user with a mix of old and updated files in the Firefox program folder.
Some of the common fixes include:
Please see our in-depth walk-through solutions below.
"Firefox error platform version is not compatible" could be caused by a cache or a third-party software. You may want to disable the third-party software by running Clean boot. Then, run Disk Cleanup to delete temporary files or the cache and then download Mozilla Firefox installer again then install. See instructions below or watch it here on YouTube.