Before I get into the “meat” of the problem (trusting sources, misinformation, etc.), here’s the official advisory from this forum cluster:
Advisory 1: drive letter reassignment possible for some users if a USB drive or an SD card is inserted while performing an in-place upgrade to Version 1903
Problem: when performing a feature update to 1903, if a USB drive or an SD card is inserted, Windows Setup may reassign drive letters for some systems.
Workaround: resolved in Windows 10 Insider Preview build 18877 (20H1), which will be backported as a cumulative update to Version 1903. If a KB alert with this fix doesn’t show up and you’re offered Feature Update to Windows 10, Version 1903, then remove any USB flash drive(s) and/or SD card(s). Or better yet, do not activate Settings/Update and Security/Windows Update/Check for updates button until this is resolved.
Advisory 2: minimum storage requirement changed
Problem: until now minimum storage requirement was 16 GB for 32-bit, 20 GB for 64-bit. Various websites (including Neowin) are reporting that the minimum storage requirement is now 32 GB for both.
Possible cause: reserved storage.
Workaround: I recommend freeing up at least 40 GB so upgrade installations can be done smoothly.
An important note: this has nothing to do with any assistive technology (I’ll address the “blindness” and “screen readers” comment in an upcoming admin notice).