"Stream HDR video" can't be enabled when switched off before upgrading to Windows 10, version 1903 or later

In Windows 10, version 1809, you turn off the Stream HDR video switch and then upgrade to Windows 10, version 1903 or later. In this scenario, you can't re-enable the Stream HDR video switch to stream high-dynamic-range (HDR) videos.

Method 1: Go back to the previous version of Windows

If you upgraded to Windows 10, version 1903 within the last 10 days, you can resolve the issue by restoring the device to Windows 10, version 1809, turning on the Stream HDR video switch, and then upgrading to Windows 10, version 1903 again.

To go back to your previous version of Windows, select the Start  button, then select Settings  > Update & Security  > Recovery  and then select Get started under Go back to the previous version of Windows 10.  (This option is only available for a limited time.) This will keep your personal files, but it'll remove apps and drivers installed after the upgrade, as well as any changes you made to settings.

Once you've turned on the Stream HDR video switch in Windows 10, version 1809, check for updates to reinstall Windows 10, version 1903.

Method 2: Modify the registry to enable the Stream HDR video switch

If you no longer have the option to restore Windows 10, version 1809, you can enable the Stream HDR video switch by modifying the registry.

1. In the search box on the taskbar, type Command Prompt, and right-click (or press and hold) Command Prompt (Desktop app) from the search results. Select Run as administrator, and then select Yes.
2. In the Command Prompt window, type the following command on a single line and then press Enter.

reg add “HKCU\Software\Microsoft\Windows\CurrentVersion\VideoSettings” /v EnableHDRForPlayback /t REG_DWORD /d 1

3. Close the Command Prompt window, and restart Windows.