If you have recently upgraded to Firefox Release 30.0 AND you are on a Non-Windows OS, you may have noticed that you are now getting a ‘401 Unauthorized’ error when attempting to log in. This is due to a change by Mozilla to disable support for NT LAN Manager Version 1 (NTLMv1) network authentication. The result of this change on a Windows based OS is that authentication will switch to NTLMv2 automatically but Firefox for a Non-Windows OS does not support NTLMv2 and instead will present the error you are receiving.
Firefox 30 was first offered to Release channel users on June 10, 2014 according to http://www.mozilla.org/en-US/firefox/30.0/releasenotes. If you did not manually download the most recent update, it was likely pushed out and auto-updated.
There have been a few discoveries that can help resolve this issue;
Option 1: Enabling NTLMv1 in Firefox 30
- Open Firefox on the Machine that you are experiencing this issue.
- Type about:config in the address bar and press enter.
- Click the ‘I’ll be careful, I promise!’ button if prompted to do so.
- Search for the string, ‘network.negotiate-auth.allow-insecure-ntlm-v1
- Double clicking this setting will change the Value from false to true.
- Once the setting has been changed, it is already saved and you can close this Tab in Firefox. Try to load you site again, and—Voila! You are now able to access your site again!
Option 2: Use an Alternate Browser
This could be Chrome, Internet Explorer, the Built-in browser; Safari, or others. This would also mean that you would have no cached content (cookies, site content, passwords, etc…) and will need to migrate this data or start fresh.
Option 3: Change Your Authentication Method
Changing to forms based authentication or Kerberos will also remedy this issue, but will require a bit of work and is a massive change to your environment. To read more on Authentication methods, please see the following articles.
- Plan for user authentication methods in SharePoint 2013
- Plan authentication methods (SharePoint Server 2010)
- Plan authentication methods (SharePoint Foundation 2010)
- Plan authentication methods (Office SharePoint Server)
Option 4: Use Windows
If you were to follow Microsoft’s Best Practices, you would open your site in the Latest version of Internet Explorer on the most recent Windows OS with all patches up-to-date. At times, I think it is easy for users to forget that SharePoint is a Microsoft Product and is designed to work best when used in conjunction with other Microsoft Products.
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