Microsoft is blocking Windows 11 upgrades if customers use applications that create registry keys using some non-ASCII characters.
As the company explains, on impacted systems such apps might be unable to open and could also cause other issues or errors in Windows 11, version 21H2 including blue screens.
"Compatibility issues have been found between apps using some non-ASCII characters in their registry keys or subkeys and Windows 11," Microsoft explains.
"Affected apps might be unable to open and might cause other issues or errors in Windows, including the possibility of receiving an error with a blue screen."
To make things even worse, in some cases, registry keys with non-ASCII characters might also be irreparable.
Even though it doesn't say it on the known issue's Windows Health dashboard entry, Microsoft has merged it with a previous bug preventing Cốc Cốc browser users to upgrade to Windows 11.
"If your organization is using Update Compliance, the safeguard ID for devices with Cốc Cốc browser is 35891494," Redmond says.
Microsoft has applied a compatibility hold to safeguard the users' experience by blocking affected Windows devices from being offered or installing Windows 11.
Customers are also advised not to attempt to manually upgrade via the Update now button or to use the Media Creation Tool until a fix is available.
Eight Windows 11 known issues are currently under investigationBesides this one, Microsoft is also investigating seven other known issues caused by hardware or software incompatibilities that could lead to system instability or crashes.
The complete list of Windows 11 known issues discovered so far includes:
The Windows 10 taskbar not upgraded to a new one designed for Windows 11
The Windows 11 Start Menu does not open
Up to 15% performance hit on AMD CPUs
Incorrect "This PC cant run Windows 11" error
Windows 11 File Explorer is using too much memory
Windows 11 compatibility issue with Oracle VirtualBox
Slower Internet speeds with Intel 'Killer' and Dell 'SmartByte' apps
To protect against potential upgrade issues, Microsoft has placed safeguard holds for some of the above issues to prevents users from upgrading to Windows 11.
Microsoft is investigating the issues, with updates to address them to be released with the October Patch Tuesday for some of them.
Windows 11 was released worldwide last week and is now rolling it out via Windows Update to new Windows 10 devices and to those pre-loaded with Windows 11.
All Windows 10 users can upgrade to Windows 11 using Windows Update if their systems come with compatible hardware. Devices are also required to run Windows 10 2004 and later AND to have installed at least the latest September 2021 updates.
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