AADFS logs shows a FATAL exception (System.Net.WebException)

Learn how to troubleshoot this AADFS issue

AADFS version 2.4 is the newest version of the AADFS installer. In some cases, customers have reported problems with older installs of AADFS not supporting TLS version 1.2 and in this case, the following FATAL exception is logged. 

FATAL: Remote server exception during DeleteHosts request: 
The underlying connection was closed: An unexpected error occurred on a send.
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 at System.Net.Sockets.Socket.Receive(Byte[] buffer, Int32 offset, Int32
size, SocketFlags socketFlags)

How to solve it

Check the AADFS version and if it is prior to version 2.4 it needs to be updated.

  • Download the newest version found in the install AADFS article
  • Stop the AADFS service
  • Create a copy of the config.json file in the AppData folder
  • Uninstall AADFS service
  • Install AADFS 2.4
  • Replace the autogenerated config.json with the old one
  • Run the AADFS service