This article shows the difference between Upgrade Warnings & Upgrade Blocks and how you can fix them if you encounter them when upgrading to Windows 7/8/10.
Windows upgrade warnings to upgrade blocks
When upgrading to Windows, Setup performs compatibility checks. If it detects problems that could affect the smooth running of the upgrade process, they are noted in the Compatibility Report.
This file is saved under Windows Compatibility Report.htm on your desktop.
If the compatibility report identifies a problem that seriously affects the upgrade process and may even lead to an undesirable result, it issues an upgrade warning.