Microsoft explains why Windows 11 still uses MS-DOS 8.3 file names

Core Windows 11 files such as kernel32.dll and ntoskrnl.exe still follow the 8.3 naming rule inherited from MS-DOS. Raymond Chen says renaming them would break programs that link to DLLs by name, while the known flaws of short names are already under control.

• The 8.3 rule allows up to 8 characters plus a 3-character extension
• The format came from CP/M in 1974 via MS-DOS
• NTFS supports 255-character names, but System32 keeps short ones
• ReFS dropped short names, and legacy apps crash on it