Offline installation is reliable when using matching source media and dism . Organizations should pre-cache the sxs folder for air-gapped systems.
If you are currently online but want to ensure the feature is enabled for future offline use: How do I install the .NET Framework 3.5? - Microsoft Q&A download net framework 3.5 offline installer
Type or paste the following command, replacing D: with your actual drive letter: DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:D:\sources\sxs : /All : Enables all parent features of .NET 3.5. Offline installation is reliable when using matching source
Installation is often the solution for the common "0xc0000135" error on Windows. Method 1: Official Microsoft Standalone Installer - Microsoft Q&A Type or paste the following
Microsoft Learn Install .NET Framework 3.5 on Windows 10 - Microsoft Learn
: The process will show a progress bar. Once finished, you will see a "The operation completed successfully" message. Method 2: Official Standalone Installer