Suddenly, your "offline installer" is anything but.

Now you have a static folder. You can zip this folder, burn it to a Blu-ray, or put it on a USB drive. To install silently without internet, create a myconfig.ini file:

A bootstrapper is a stub. When you run it, it checks your architecture, checks for dependencies (like .NET Framework or Visual C++ Redistributables), and then reaches out to Microsoft’s Content Delivery Network (CDN) to download the actual .cab files (cabinet files) in real-time.

Copy the contents of C:\SQL_Offline_CU (specifically the Setup folder and Patch directory) into C:\SQL_Offline_Base , overwriting when prompted.

Open CMD as Administrator. Do not double-click the CU. Run: C:\Downloads\SQLServer2019-KB5029379-x64.exe /x:C:\SQL_Offline_CU

Have you ever been burned by the online bootstrapper during a critical outage? Let me know in the comments below.