Last week I wrote a tip for anyone getting “This PC can’t be upgraded to Windows 10”
when trying to upgrade to the Windows 10 May 2019 Update. Initially I thought it was a problem restricted to SD cards and the Surface Pro 3, but it turns out Microsoft have blocked the May 2019 Update from installing if you have a SD memory card installed or external USB storage device. The reason Microsoft blocking the update is that drive letter could be reassigned during the upgrade, so an SD card may have had a D letter and after the upgrade it could be E. This could break shortcuts so Microsoft have placed the block on the install.
To get around the block just remove the drive or SD card and let the install go ahead. After the install, you can re-insert the drive. You can of course just wait for Microsoft to fix the issue and then you will get the update when Microsoft remove the block.
Details from Microsoft:
Inappropriate drive reassignment can occur on eligible computers that have an external USB device or SD memory card attached during the installation of the May 2019 update. For this reason, these computers are currently blocked from receiving the May 2019 Update. This generates the error message that is mentioned in the “Symptoms” section if the upgrade is tried again on an affected computer.
Example: An upgrade to the May 2019 Update is tried on a computer that has the October 2018 update installed and also has a thumb drive inserted into a USB port. Before the upgrade, the device would have been mounted in the system as drive G based on the existing drive configuration. However, after the upgrade, the device is reassigned a different drive letter. For example, the drive is reassigned as drive H.
Note The drive reassignment is not limited to removable drives. Internal hard drives can also be affected.