Error Update Big Sur 11.3 from Big Sur 11.2.3

There are several options.

Adjustment for Wifi update - shutdown computer and move as close the Router as possible. Connect to charger. Disconnect ALL Other devices using the Wifi - want the Maximum Bandwidth for this computer.

Suggest - restart Router . Restart computer in Safe Mode - Shift - Key immediately at startup. It does a Repair Disk, clears cache files and load only Apple Software - load slowly - Normal. Once in Open Apple Apps Store and find Big Sur and download. Try not to let computer go to sleep mode or Screen Save to activate. Be patient as one knows it Big Sur is 12.18 GB size. There are often periods where it seems to pause the download , normal be patient as countdown clock may say 15 minutes but in Real Time could be 30 - 45 minutes. This can and will happen several time in the process. If all goes well. it will successfully download and attempt to Launch. Do NOT allow it to start - Quit the Installer. Check Applications Folder for new App called Install Bug Sur. Make a copy to External Drive - future usage. Now, restart again in Safe Mode - then launch the Installer.

Hi,

Try to update to 11.3 by wired internet connection with USB-C to Gigabit Ethernet adapter which is available at online Apple Store.

https://www.apple.com/shop/product/HJKF2ZM/A/belkin-usb-c-to-gigabit-ethernet-adapter?fnode=cb4c30fbaf1514c104f8ea42b847926ec58293e06892400461a35adfb4a7f01ee60a522e1553e91dd17db0cc2bd522f707085a533e22f4a02a8410ec3931ead6d3c43bb77540c04b90b5ecda35f9574fc493e6a29a428f87de6a2ad5c2d423151d29bf201d7759ac3ab164a4dde3953a&fs=f%3Dadapter%26fh%3D4595%252B45b0

Do not know if any one has launched a Lawsuit Against Apple and this is not within the scope of these Support Forums.

As for you specific Software issue - one could always use another Qualifying ( Big Sur ) Apple Computer at another location that has a Speedy and Reliable Internet Connection to download the Full Installer ( should be Big Sur 11.3 ) form the Apple Apps Store and Create A Bootable Installer of BS 11.3. Drag the USB Installer back to this computer - Option at Bootup >> choose the Installer and run the update.

I am having a lot of problems since installing the infamous Big Sur a week ago (eg. My SD slot no longer registers as having a camera card in it). I have twice downloaded the update 11.3 (taking 9 hours with my slow internet). Each time when it reached completion and says the 5.71GB have been downloaded it then says an error has occurred and fails, telling me to try again! Has anyone sued Apple for releasing such an error filled operating system? It beggars belief really and I don't know how to proceed.

Is that the only option?