There was a similar thread, you can try the answers : Install failed .NET Framework 4.7.2 and 4.8 (Cannot find the file specified)
4.8 framework not installing
I have tried so many times but the 4.8 framework is not installing it shows "The system cannot find the file specified.
And here is my oq file,
OS Version = 10.0.17134, SP = 0.0, Platform 2
OS Description = Future OS - x64
MSI = 5.0.17134.1
Windows servicing = 10.0.17134.1
CommandLine = G:\40ee045a03d1fb0e2a\Setup.exe /x86 /x64 /redist
TimeZone = Central Daylight Time
Initial LCID = 1033
Using Simultaneous Download and Install mechanism
Operation: Installing
Package Name = Microsoft .NET Framework 4.8 Setup
Package Version = 4.8.04115
User Experience Data Collection Policy: Disabled
Number of applicable items: 6
Exe (G:\40ee045a03d1fb0e2a\SetupUtility.exe) succeeded.
Exe Log File: dd_SetupUtility.txt
Exe (G:\40ee045a03d1fb0e2a\SetupUtility.exe) succeeded.
Exe Log File: dd_SetupUtility.txt
Exe (G:\40ee045a03d1fb0e2a\x64-Windows10.0-KB4486153-x64.cab) failed with 0x2 - The system cannot find the file specified. .
Exe (G:\40ee045a03d1fb0e2a\x64-Windows10.0-KB4486153-x64.cab) failed with 0x2 - The system cannot find the file specified. .
Exe (G:\40ee045a03d1fb0e2a\x64-Windows10.0-KB4486153-x64.cab) failed with 0x2 - The system cannot find the file specified. .
Exe (G:\40ee045a03d1fb0e2a\x64-Windows10.0-KB4486153-x64.cab) failed with 0x2 - The system cannot find the file specified. .
Final Result: Installation failed with error code: (0x00000002), "The system cannot find the file specified. " (Elapsed time: 0 00:01:19).