As a Part of my pre-flight check for Vcenter upgrades i like to mount the ISO and go through the first 3 steps, during this I noticed the installer cannot connect to the source appliance with this error
2019-05-01T20:05:02.052Z - info: Stream :: close 2019-05-01T20:05:02.052Z - info: Password not expired 2019-05-01T20:05:02.054Z - error: sourcePrecheck: error in getting source Info: ServerFaultCode: Failed to authenticate with the guest operating system using the supplied credentials. 2019-05-01T20:05:03.328Z - error: Request timed out after 30000 ms, url: https://vcenter.companyABC.local:443/ 2019-05-01T20:05:09.675Z - info: Log file was saved at: C:\Users\MCbits\Desktop\installer-20190501-160025555.log
trying to reset via the admin interface or the DCUI didn’t work, after digging around found a way to reset it by forcing the vcenter to boot in to single user mode
Take a snapshot or backup of the vCenter Server Appliance before proceeding. Do not skip this step.
Reboot the vCenter Server Appliance.
After the OS starts, press e key to enter the GNU GRUB Edit Menu.
Locate the line that begins with the word Linux.
Append these entries to the end of the line: rw init=/bin/bash The line should look like the following screenshot:
After adding the statement, press F10 to continue booting
Vcenter appliance will boot into single user mode
Type passwdto reset the root password
if you run into the following error message
"Authentication token lock busy"
you need to re-mount the filesystem in RW, which lets you change between read-only and read-write. this will allow you to make changes
So recently I ran into this annoying error message with Exchange 2016 CU11 Update.
Exchange 2016 upgrade from CU8 to CU11
Exchange binaries are installed under D:\Microsoft\Exchange_Server_V15\..
Microsoft.PowerShell.Commands.GetItemCommand.ProcessRecord()". [12/04/2018 16:41:43.0233]  [ERROR] Cannot find path 'D:\Microsoft\Exchange_Server_V15\UnifiedMessaging\grammars' because it does not exist. [12/04/2018 16:41:43.0233]  [ERROR-REFERENCE] Id=UnifiedMessagingComponent___99d8be02cb8d413eafc6ff15e437e13d Component=EXCHANGE14:\Current\Release\Shared\Datacenter\Setup [12/04/2018 16:41:43.0234]  Setup is stopping now because of one or more critical errors. [12/04/2018 16:41:43.0234]  Finished executing component tasks. [12/04/2018 16:41:43.0318]  Ending processing Install-UnifiedMessagingRole [12/04/2018 16:44:51.0116]  CurrentResult setupbase.maincore:396: 0 [12/04/2018 16:44:51.0118]  End of Setup [12/04/2018 16:44:51.0118]  **********************************************
Ran the Setup again and it failed with the same error while going though the log files i notice that the setup looks for this file path while configuring the "Mailbox role: Unified Messaging service" (Stage 6 on the GUI installer)
There was no folder present with the name grammarsunder the Path specified on the error
just to confirm, i checked another server on CU8 and the grammars folder is there.
Not sure why the folder got removed, it may have happened during the first run of the CU11 setup that failed,
My first thought was to copy the folder from an existing CU8 server. but just to avoid any issues (since exchange is sensitive to file versions) I created an empty folder with the name "grammars" under D:\Microsoft\Exchange_Server_V15\UnifiedMessaging\
Ran the setup again and it continued the upgrade process and completed without any issues...¯\_(ツ)_/¯
[12/04/2018 18:07:50.0416]  Ending processing Set-ServerComponentState [12/04/2018 18:07:50.0417]  Beginning processing Write-ExchangeSetupLog [12/04/2018 18:07:50.0420]  Install is complete. Server state has been set to Active. [12/04/2018 18:07:50.0421]  Ending processing Write-ExchangeSetupLog [12/04/2018 18:07:50.0422]  Finished executing component tasks. [12/04/2018 18:07:50.0429]  Ending processing Start-PostSetup [12/04/2018 18:07:50.0524]  CurrentResult setupbase.maincore:396: 0 [12/04/2018 18:07:50.0525]  End of Setup [12/04/2018 18:07:50.0525]  **********************************************
Considering cost of this software M$ really have to be better about error handling IMO, i have run in to silly issues like this way too many times since Exchange 2010.