Unable to connect to the Portal or Workflow Manager Server. Please check the connection

Error Message

When launching the Workflow Manager web app from the app launcher in Portal for ArcGIS, you may receive the error message:

"Unable to connect to the Portal or Workflow Manager Server. Please check the connection."

Additionally, network traffic may show that a request to https://server.domain.com/server/workflow/checkStatus returns:

"500 - Could not access any server machines. Please contact your system administrator."

However using a browser to access the checkStatus endpoint through the port (https://server.domain.com:13443/workflow/checkStatus), returns "success=true".

Cause

This issue occurs because Portal for ArcGIS cannot establish communication with Workflow Manager Server on the ArcGIS Server machine with the Workflow Manager server role.

Solution or Workaround

The first thing to check is the certificates used by Portal for ArcGIS and ArcGIS Server, as well as the web server (either Java Tomcat or Microsoft IIS).

• Is the expiration date valid?
• Are all machine fully-qualified domain names (FQDNs) listed as subject alternative name (SAN) values?
• Is the Portal for ArcGIS certificate imported into ArcGIS Server and vice versa? Also, are the root and intermediate certificates imported into each site?

Next, use Windows PowerShell Test-NetConnection. See the Microsoft documentation for the NetTCPIP module to check connectivity for the following route:

• You will need to check connectivity from the ArcGIS Web Adaptor machine:
• In Windows PowerShell on the web adaptor machine:

Test-NetConnection -ComputerName <wmx-machine-FQDN> -Port 13443 -InformationLevel "Detailed" 

If this test fails, adjust network firewall rules so that the test succeeds. You should then be able to successfully launch the Workflow Manager web app from the Portal for ArcGIS app launcher.