Error 0x300006xc - Unable To Connect Via Microsoft Remote Desktop Protocol On A MAC

Error 0x300006xc - Unable to connect via Microsoft Remote Desktop Protocol app (MRDP) on a MAC

Issue Description:   

       Cannot launch the server and sometimes receives an error:

"The certificate couldn't be verified back to root certificate. Your connection may not be secure"

Requirements to Complete this Process:

• Local MAC credentials. 
• Credentials to log in to the server from the Microsoft Remote Desktop app (MRDP). 

Steps and Screenshots:

1. Check the dock and make sure the MRDP application is completely closed. 
2. If you see the icon from the dock, right-click on it then click Quit. 
   
3. If it is not quitting,
   • Click on the MRDP application
   • Click on the Apple icon
   • Click on Force Quit... and force quit Microsoft Remote Desktop. 
4. Relaunch Microsoft Remote Desktop to log into the server.

Additional URLs or References (as needed):

- Cross Reference Version of the Microsoft Remote Desktop application installed to

Microsoft App Center or What's new in the macOS client for version information and related bug fixes.