ESXi (in this case version 6.7.0) can appear to hang / freeze during the boot up sequence at the following step:
dma_mapper_iommu loaded successfully
However the system is otherwise fully responsive (e.g., via vSphere). The root cause was that the video card used for displaying the local console had been enabled for passthrough.

When trying to update/upgrade ESXi 6.7.0 Update 1 to Update 2 (via software profile update command) you may run into the following error:

[InstallationError]
[Errno 28] No space left on device
vibs = VMware_locker_tools-light_10.3.5.10430147-12986307
Please refer to the log file for more details.

The solution is to manually install VMware_locker_tools package by following these steps via SSH on the host:

1. cd /tmp
2. wget http://hostupdate.vmware.com/software/VUM/PRODUCTION/main/esx/vmw/vib20/tools-light/VMware_locker_tools-light_10.3.5.10430147-12986307.vib
3. esxcli software vib install -f -v /tmp/VMware_locker_tools-light_10.3.5.10430147-12986307.vib
4. Once you receive verification that the locker tools package has been installed successfully, try the profile update command again to patch ESXi.
   Note – in some cases the installation of this VIB may be skipped by the server and you receive the message: Host is not changed.  If so then simply try the profile update command again and you should not receive Errno 28 related to the locker tools VIB.

When trying to update/upgrade ESXi 6.7 (via software profile update command) you may run into the following error message:

[OSError]
[Errno 28] No space left on device
Please refer to the log file for more details.

The solution is to set the host swap to use a datastore. In vSphere Web Access:

1. Navigate to Host->Manage->System->Swap. At this point, the Datastore setting should be set to No.
2. Choose Edit Settings, select a valid Datastore in the drop down menu, then Save.
3. Now you are ready to issue the profile update command again to patch ESXi

New install of Windows Server 2016 (build 14393.447 from ISO SW_DVD9_Win_Svr_STD_Core_and_DataCtr_Core_2016_64Bit_English_-3_MLF_X21-30350 with no updates) had an issue where Windows Updates would hang / freeze indefinitely at 0% progress. 

When Windows Update ran it would briefly flash a list of updates that were available before disappearing. Then it would simply state “Updates are available” with a progress of 0%.  Also the folder C:\Windows\SoftwareDistribution was roughly 500MB in size. 

The solution was to re-enable the Windows Firewall which had been disabled immediately after the initial install and prior to running Windows Update for the first time. After enabling Windows Firewall, restart the Windows Update service (in services.msc) and then have Windows check for updates again.

Attempting to activate / convert an evaluation copy of Windows Server 2016 (specific build 14393.rs1_release.161220-1747) to the full version using a valid retail key, resulted in the following error:

This edition cannot be upgraded.

A solution is to perform the activation via console with the following command:

Dism /online /Set-Edition:<Edition> /AcceptEula /ProductKey:<ProductKey>

where <Edition> is either ServerDatacenter or ServerStandard and <ProductKey> is your product key with dashes.

The Deployment Image Servicing and Management tool may indicate that it has finished installing product key, but then hang at 10.0% on the next step:

Removing package Microsoft-Windows-Server.....

If after 30 minutes it has not progressed – cancel the entire process, then repeat the same steps and it should go through the second time.

Brand new install of Windows 2016 Server Evaluation without any updates installed, specific build 14393.rs1_release.161220-1747 (also 14393.447)  Attempting to remote desktop to the server from a Windows 10 client resulted in an error:

An authentication error has occurred.
The function requested is not supported
Remote computer:x.x.x.x
This could be due to CredSSP encryption oracle remediation. For more information, see https://go.microsoft.com/fwlink/?linkid=866660

Note: For Windows 7 clients, the last line above in red color will be omitted from the error message.

This happened for both Datacenter and Standard installs of the same build. The fix is to simply install all available updates from Windows Update, rebooting in between as necessary. After all updates have been installed, try the remote connection again.

QuickCam 4000 shows up as “Unknown device” in Windows 7 Device Manager
(USB\VID_046D&PID_08B2)

Download the 64-bit driver from Logitech
ftp://ftp.logitech.com/pub/techsupport/quickcam/qc1051enu_x64.exe

Unpack this .exe file to a folder using 7zip, WinRAR, etc.

In Device Manager right click the device, update driver, Browse my computer and point it to this folder containing the unpacked files.

Group Policy options will let you disable the button for error reporting to Microsoft (Check online for a solution and close the program) but there is no option in Group Policy to disable the debugging button. To disable the “Debug the program” button that is shown in the Windows Problem Reporting window after a program crashes, there are two registry entries that must be modified. One controls it for 64-bit program crashes and the other for 32-bit program crashes:

64-bit
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AeDebug]

32-bit
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\AeDebug]

Under each of these keys, you will see a string titled Debugger.  Rename it (e.g., Debugger.bak) and the debug button will no longer show up.

Strange issue with Windows Update occurred. In this case Windows Server 2012 R2 was trying to install 2 updates for Office 2010 but was failing.

KB4461579 failed with Code 780
KB2553332 failed with Code 780

First it turned out that a 64-bit version of Microsoft Access database engine 2010 had managed to get installed which does not play nice with 32-bit versions of MS Office on the same machine.  The 64-bit engine was uninstalled and then replaced with the 32-bit version.  When the 64-bit version was uninstalled, it also removed the 64-bit version of the Office Source Engine service from the system that was showing up in services.msc. However after this change, the 2 Windows updates listed above were still failing.

Also installed on the system was Microsoft Access 2010 Runtime.  Within Programs and Features of the Control Panel, performing a Change->Repair option on it completed fine, but wanted a reboot.  After rebooting, the two Windows updates listed above were then able to complete successfully.

Background information:  swapped out a CPU during an upgrade (old CPU DDR3-1333, new CPU DDR3-1600).
After that the system was booted using an Ubuntu Live CD without any obvious problems, but ESXi installer was crashing with Pink Screen of Death (PSOD). Next step was to test with MemTest86 (in this case V8.1 build 1000). The system would repeatedly freeze on Test 0 [Address test, walking ones, 1 CPU] with no errors reported. To fix, all that was needed was a CMOS / BIOS reset (to defaults). After that MemTest86 and ESXi installers ran through without any problems.