Unable to update to macOS Tahoe from macOS Big Sur on MacBook Air (M1, 2020)

Boilerplate support from Apple

If an error occurred while updating or installing macOS

More detailed support

There are factors:

Some which are beyond your control and those which are totally under your control

Like poor Wifi connection

Slow wifi connection

Too many other people downloading at the same time and Apple  Servers are overloaded

Software on the computer interfering with the download process including AntiVirus Software

Notation: Disabling the AV Software may or may not solve the issue. Removal of the AV Software may increase the chances of the download to perform as expected.

Running behind a VPN which may increase Packet losses or corruption of the download 

VPNs also will usually slow down the Internet Speed by about 30 %

Turn off any Third Party Two Way Firewall and try again 

If via wifi  & too many Other devices using the wifi at the same time reducing the Bandwidth to your computer. 

Best Results are via Ethernet Cable to Router

Restart in Safe Mode. This will perform a Disk Repair, clear cache files and only load Apple Software, extensions and fonts. The boot up will be slow and can take some time - Normal 

Try Again using the Software Update Applet in System Preferences / Setting 

Worst case - Restart inRecovery Mode and choose Reinstall macOS. 

This in theory will pull the latest version of macOS this computer qualifies to run 

From any browser download the following

https://swcdn.apple.com/content/downloads/51/26/122-77688-A_F01L27Y7Q6/7e8t8w89evbl6sgkoy9jhrmw2tqfkhjsd9/InstallAssistant.pkg

Boot macOS Safe Mode:

Start up your Mac in safe mode - Apple Support

Double-click the .pkg

That will create Applications -> Install macOS Tahoe

Double-click the “Install macOS Tahoe” app

when finished, delete the .pkg to get back your storage.

What error message does it display?