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Authentication errors occur when client doesn't have TLS 1.2 support


As previously communicated in the Microsoft 365 Admin Center (for example, communication MC240160 in February 2021), we're moving all online services to Transport Layer Security (TLS) 1.2+. This change started on October 15, 2020. Support for TLS 1.2+ will continue to be added to all Microsoft 365 environments for the next several months. If you haven't taken steps to prepare for this change, your connectivity to Microsoft 365 might be affected.

.NET Framework not configured for TLS 1.2


You experience one or more of the following errors when you access SharePoint:

Token request failed. ---> System.Net.WebException: The remote server returned an error: (401) Unauthorized. at System.Net.HttpWebRequest.GetResponse()

System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a send.

System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host.

The Business Data Connectivity Metadata Store is currently unavailable.


For more information about how to configure .NET Framework to enable TLS 1.2+, see Configure for strong cryptography.

OS doesn't have TLS 1.2 enabled


Authentication issues occur in older operating systems and browsers that don’t have TLS 1.2 enabled, or in specific network configurations and proxy settings that force legacy TLS protocols.


Windows 10

Solution 1: Check cipher suites settings

Even after you upgrade to TLS 1.2, it's important to make sure that the cipher suites settings match Azure Front Door requirements, because Microsoft 365 and Azure Front Door provide slightly different support for cipher suites.

For TLS 1.2, the following cipher suites are supported by Azure Front Door:


To add cipher suites, either deploy a group policy or use local group policy as described in Configuring TLS Cipher Suite Order by using Group Policy.


Edit the order of the cipher suites to ensure that these four suites are at the top of the list (the highest priority).

Alternativley, you can use the Enable-TlsCipherSuite cmdlet to enable the TLS cipher suites. For example, run the following command to enable a cipher suite as the highest priority:

Enable-TlsCipherSuite -Name "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384" -Position 0

This command adds the TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 cipher suite to the TLS cipher suite list at position 0, which is the highest priority.


After you run Enable-TlsCipherSuite, you can verify the order of the cipher suites by running Get-TlsCipherSuite. If the order doesn't reflect the change, check if the SSL Cipher Suite Order Group Policy setting configures the default TLS cipher suite order.

For more information, see What are the current cipher suites supported by Azure Front Door?.

Windows 8, Windows 7 or Windows Server 2012/2008 R2(SP1)

If you're using Windows 8, Windows 7 Service Pack 1 (SP1), Windows Server 2012 or Windows Server 2008 R2 SP1, see the following solutions.

Network drive mapped to a SharePoint library


Authentication issues or failures occur when you try to use a network drive that's mapped to a SharePoint library.


The issue might occur because of the operating system in use and whether the web client supports TLS 1.2. Support for TLS 1.2 is as follows:

Browser doesn't support TLS 1.2


Authentication issues or failures to access SharePoint from known apps that don't support TLS 1.2+ occur. The following browsers don’t support TLS 1.2:

  • Android 4.3 and earlier versions
  • Firefox version 5.0 and earlier versions
  • Internet Explorer 8-10 on Windows 7 and earlier
  • Internet Explorer 10 on Windows Phone 8
  • Safari 6.0.4/OS X10.8.4 and earlier versions


Upgrade to a later version of the browser.

Azure App Service doesn't use the latest version of TLS and .NET Framework


Authentication issues when you use Azure App Service.


  1. Set the minimum TLS version for your App Service instance to TLS 1.2. For more information, see Enforce TLS versions.
  2. Make sure that you're using the latest version of .NET Framework.

Hybrid search fails to crawl or return results


You experience one or more of the following issues when you use hybrid search in SharePoint in Microsoft 365:

  • Crawling fails.
  • No result is returned.
  • You receive an error message, such as "An existing connection was forcibly closed".


To fix the issues, see Hybrid search fails to crawl or return results.