When logged in as Administrator in a Windows 10 or 11 machine, when you try to add a shared printer, you get the error:

That didn't work. We can't install this printer right now. Try again later or contact your network administrator for help. Error: #740.

The underlying problem is this: Error 740 means: "The requested operation requires elevation".

This is a problem as you are already logged in as Administrator. So the solution is to start the "Add Printer Wizard" as Administrator. To do this:

• Open a cmd box as Administrator, then run
• rundll32 printui.dll,PrintUIEntry /il

Go through the "Add Printer Wizard" as normal. This time, it will work without error.