The 26H2 update is just a small enablement package used to install the 26H2 update, many people are reporting problems trying to install that update, the error 0x80072efd indicates a problem contacting the Microsoft servers.
The best option is to open the Settings App.
Go to System - Recovery.
Click the 'Reinstall Now' button in the 'Fix problems with Windows Updates' section, then wait for that process to complete, this process should fix your Windows updates process and does not affect your files, settings or installed apps.