I also had to configure the web.config ([2.9.0] Broken Page - Missing files? [RESOLVED]). On top of that I got the following error:
Start-UDDashboard : The Win32 internal error "The handle is invalid" 0x6 occurred while setting character attributes for the console output buffer. Contact Microsoft Customer Support Services.
To solve that issue, i had to set to following configuration on top of the dashboard.ps1
$WarningPreference = "SilentlyContinue"
This probably has something to do with -AllowHttpForLogin. I leave HTTPS to Azure and not to UD. I am in the understanding that should be sufficient. If this is not OK, please let me know.
I think the problem can also be solved by using stdoutLogEnabled=“false” in the web.config