Exchange SE install failing due to missing c:\windows\temp\exchangesetup\mailbox\address structure

Hello Jason Cooper

Based on my research, this issue can sometimes be resolved by simply rerunning the setup, as the process may trigger a reboot and then relaunch the Exchange setup package automatically.

If rerunning the setup does not help, you can try the following steps:

• End .NET optimization processes (or wait until they finish): Open Task Manager > Details tab, and end both mscorsvw.exe processes if they are running.
• Manually delete the folder: C:\Windows\Temp\ExchangeSetup Or open an elevated Command Prompt and run: rd /s /q "C:\Windows\Temp\ExchangeSetup"
• Fix permissions on the Temp folder. In the same elevated Command Prompt, run: icacls "C:\Windows\Temp" /grant Administrators:(OI)(CI)F /grant SYSTEM:F /T
• Temporarily disable Microsoft Defender or any antivirus (real-time protection).
• Rerun the Exchange setup. You can also extract the setup files first for a cleaner run:

Setup.exe /Extract:C:\ExchangeSetupSource
cd C:\ExchangeSetupSource
Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /Mode:Install 

Please try these steps and feel free to share any updates after testing.

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