Error "connection To Master Server Failed" Upon Testing The Agent Connection To The Master Server Url In The Registration

Published: 01 Jul 2020
Last Modified Date: 08 Jul 2022


When testing the Agent connection to the Master Server URL in the registration phase, the connection fails with the error below:

Master Server URL Connection Failure



  • Tableau Resource Monitoring Tool 2020.2.0
  • Windows Server


There may be a couple different causes for this error.  Please consult with the two possible solutions below.

Solution 1:
Allow port 443 outbound connections from the Agent machine and inbound for the Master server.

Solution 2:
Adjust the registry to include RSA/SHA512 and ECDSA/SHA512 

1. Open the registry with regedit.exe
2. Navigate to HKEY_LOCAL_MACHINE SYSTEM\CurrentControlSet\Control\Cryptography\Configuration\Local\SSL\00010003 Functions
3. Add the following entries on their own line below the existing values: RSA/SHA512 and ECDSA/SHA512
Cryptograhpy Functions
4. Save and reboot the machine for the changes to take effect. 


Port 443 may be blocked by the firewall preventing HTTPS connections to the Master machine.

With RMT HTTPS enabled, the self-signed certificate uses the SHA512 algorithm and on machines without this supported, connections fail.


Additional Information

Windows Application Event Viewer logs may show a .NET error:

System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception.
 ---> System.Security.Authentication.AuthenticationException: Authentication failed, see inner exception.
 ---> System.ComponentModel.Win32Exception (0x80090308): The token supplied to the function is invalid
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