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There was a recent Symantec Antivirus signature update on September 12 that causes Firefox to crash at startup. We are working with Symantec to fix this issue and recommend one of the following workarounds until a fix by Symantec is commonly available.
Update to a current version of Firefox
As the latest available versions of Firefox are reportedly not affected by this crash at startup, we recommend that all users update to the latest version.
You can download Firefox through the following links:
- Windows 7, 8, 10: https://www.mozilla.org/en-US/firefox/all/
- Windows XP, Vista: https://download.mozilla.org/?product=firefox-48.0.2-sha1&os=win&lang=en-US
Firefox 45.3.0esr for organizations:
Roll-back signature updates to a prior version
If Symantec is used in an enterprise environment it may be possible to roll-back client intrusion prevention signature updates to a prior state (instructions are here: https://support.symantec.com/en_US/article.TECH102935.html).
You can also refer to the following post in Symantec's support forum: http://www.symantec.com/connect/forums/firefox-problem-after-sep-update
Check for new Symantec updates
As we expect Symantec to publish a fix that addresses the stability issues soon, please check for available program and signature updates in your Symantec product regularily.