I just did a fresh install of Bitbucket v5.4.1 with a MySQL External database on Windows Server 2016. The install went just fine but navigating through the screens was tortuously slow and they eventually stopped all together.
Checking the system logs I found this:
The application-specific permission settings do not grant Local Activation permission for the COM Server application with CLSID
{D63B10C5-BB46-4990-A94F-E40B9D520160}
and APPID
{9CA88EE3-ACB7-47C8-AFC4-AB702511C276}
to the user TRTC1143\atlbitbucket SID (S-1-5-21-3431148963-857714745-2097211096-1001) from address LocalHost (Using LRPC) running in the application container Unavailable SID (Unavailable). This security permission can be modified using the Component Services administrative tool.
I was able to trace that back to the RunTimeBroker. Unfortunately, I did not, by default, have permissions to mess with the RunTimeBroker permissions.
This website led me to the fix - THE HERO
TLDR;