USB drives are confusing the May 2019 update for Windows 10

Presumably in a few weeks, Microsoft will begin rolling out the May 2019 update for Windows 10, but like the October 2018 update that came before it, it may arrive with some annoying issues. One of those is the inability to handle an upgrade if a USB flash drive or SD card is plugged in.

It seems odd that in this day and age, Windows can get confused over something as commonly used as external storage. Nevertheless, it's happening. To deal with it, Microsoft is blocking the update from installing on PCs when it recognizes the presence of a USB flash drive or SD memory card. What gives?

As spotted by The Register, a support article pins the problem on mismanaging drive letter assignments. When you plug an external drive into your PC, it gets assigned a letter. For whatever reason, the May 2019 update for Windows 10 can muck this up when there's an external drive attached.

For example, let's say you have a USB flash drive plugged in and that it's recognized as drive G. After the upgrade, Windows might reassign it as drive H.

That may seem harmless, but Microsoft notes in the support document that when this happens, Windows might also reassign internal drives as well, not just removable ones. That can cause major headaches that can't be solved with ibuprofen.

"For this reason, these computers are currently blocked from receiving the May 2019 Update," Microsoft says.

The good news is that Microsoft caught this before it starting pushing out the May 2019 update, which means it currently only affects members in the Windows Insider program. Microsoft also says that the issue will be resolved in a future servicing update for Windows 10. However, it's not clear if that will come before or after the update is made available to the public.