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- Open the Start menu
- Type "About" and click on the result "About your PC":
- Towards the bottom of the window that opens it will have "Version" - if it shows "21H1" or "21H2", then it is running a sufficiently up-to-date version of Windows 10. If it has a lower number (e.g. 1803 or 1909) then you will need to install an update:
(Version too old, update required) (Version 21H1, able to join)
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