Mixed Exchange Server ECP portal not accessible

prashanthpurushotham 

Thank you for the information you sent.
After review, there are no missing arbitration mailboxes, which is normal.

[Action Item]
To execute these PowerShell scripts, follow these steps,
Open PowerShell as administrator and use the ‘cd’ command to navigate the Exchange ‘Bin’ directory.
For instance,
cd “C:\Program Files\Microsoft\Exchange Server\V15\Bin.”

Then execute the following commands to run the PowerShell scripts to fix the configuration issues.

.\UpdateConfigFiles.ps1
.\UpdateCAS.ps1

This may take a while to finish.
Once done, restart the server and check if the HTTP 500 error is resolved and ECP/EAC is accessible.

TaeYounAnn 

prashanthpurushotham 

I would like to know the result value of the following execution.

Get-Mailbox -Arbitration