Starting with the May 2019 Update, the desktop version of Windows 10 will require a hard drive with at least 32GB of space to install correctly.
Windows 10 version 1903, May 2019 Update, is expected to release to the public in late May, and while the new feature update should install without issues on devices already running any release of Windows 10, Microsoft is making changes to the minimum storage requirements.
According to an updated support document, the company reveals that starting with the May 2019 Update, the desktop version of Windows 10 “must include a storage” of 32GB or greater for the 32-bit and 64-bit version.
This is around 12GB more storage than the previous 20GB minimum requirement.