Should the WIX UpgradeCode be different between an x64 and an x86 version of a product?

I'm assuming YES.

I have an installer for the x86 version, I'm building the installer for the x64 version.

I'm trying to figure out the gotchas. So far it looks pretty straightforward. I feel like they ought to be different UpgradeCodes. I'll need to chec开发者_如何学JAVAk for the VersionNT64 property within a Condition to validate the install.

<Condition Message="This package can be installed only on an x64 version of Windows.">
  VersionNT64
</Condition>

Any other hints?

I would go ahead and say that yes you should probably have different upgrade codes for the two installers unless you have a specific need for them to be the same.

One scenario I can think of where matching upgrade codes may be useful is if you have previously shipped only a x86 version that was able to install on both 32-bit and 64-bit operating systems. In such a case, having a x64 version with the same upgrade code would allow you to easily handle upgrades from the older x86 to the new x64 version on 64-bit operating systems.

Edit:

I forgot to mention that you can also use the "Msix64" property to determine bitness. It's also unnecessary to add an install condition to the x64 version, since attempting to install it in a 32-bit OS will result in an error message from the Windows Installer service.

Currently I only use one condition in the x86 version of the installer

<Condition Message="You are attempting to install the x86 version in a 64-bit OS">NOT Msix64</Condition>

From my recall I can say that the code for the x86 version would be based on the code used on some 80x86 and later processors for the 16 to 32bit versions while the x64 would be different code for the 64 bit implementation asssuming it is x64 and not IA-64 or Intel64 code. The loader would be different and you may need to check the status of values in the BIOS (if present) and some environment variables to determine if 32 or 64bit mode is in operation on a computer, including the one you are developing the loader on if it supports one or both of the modes.