Firefox v30 breaks SharePoint authentication on non-Windows based browser


NTLMv1 auth has been disabled, NTLM support on non-Windows platforms is now deprecated

The support for the NT LAN Manager version 1 (NTLMv1) network authentication has been disabled because it’s known as insecure. Companies and organizations still deploying the older protocol should upgrade to NTLMv2. See Honza Bambas’ blog post and Jason Duell’s post to the dev-planning list for details.

This is affecting SharePoint-based or IIS-backed intranet applications. If you encounter any problems on Firefox 30 or later, you can manually enable NTLMv1 using a preference. Note that NTLMv2 is not supported on non-Windows platforms, so OS X and Linux users have to toggle the preference to continue using NTLMv1 as below, though the NTLM auth support on non-Windows platforms is considered deprecated.

How to enable NTLMv1: type about:config in the location bar, click the “I’ll be careful” button, find network.negotiate-auth.allow-insecure-ntlm-v1, double-click on it to change the value to true.

Another workaroud here is using Firefox 24 ESR that still enables the NTLMv1 auth.

authentication, firefox 30, ntlm, ntlm2

Comments (2)

  • We had to figure this out.. Thanks for the post.. I am all for disabling insecure protocols, but you can’t just turn it off if that is the only option for people to use. This also impacted ADFS for office 365. Next version of ADFS will be forms based which should address other issues we are having with Windows integrated login on non Windows machines like not being able to sign out of Office 365 EVER..

    • Yeah agreed. On the Office 365 sign out issue: I agree it’s pretty stubborn, you’d think a browser cache clear + browser restart + Windows Credential clear would do the trick, knowing what most know about how web credentials/sessions are typically maintained. It might be worth your while though to try all the steps detailed on

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