Unable to install macOS Big Sur on my iMac

Have same problem and worked with 3 techs in support for hours and haven’t solved. They get me to same place I have been at and then leave you. Error encountered a problem during install. I have a 1Tb drive and excellent internet connection

The iMac is a mid 2014 21.5” which Apple indicates is capable to run Big Sur. It has a 1Tb hard drive. It currently is running Catalina 10.15.7 for over a year. It is Ethernet connected and typically downloads 350mbs. Able to download 12.41gb of 12.41gb. At that point it appears the system may be trying to install but gives msg An error occurred while installing the selected update. I have been at that point several times.

Along with one of Apple support techs we shut down system and restarted in Safe Mode. After downloading Big Sur we got the same error message. Not getting the Install message. During that session we checked out the drive and it’s fine.

Along with Apple support tech we did a start in Safe Mode and tried the download. We downloaded 12.41gb of 12.41gb but got the same Error msg. We even checked out the drive which we ok. Never get the install message.

Thanks for everyone that offered suggests to solve my problem downloading and installing Mia big sur. Attempted most but none weee successful. Turned to Apple support and worked with 4 tech. Had no positive results with 3. Last tech was very knowledgable and took my system directly to Apple severs. Start in Safe mode then hold down Control,Command, the R key. Seemed to eliminate the glitch between download and install. Ended up at my local store and they did same step and was successful

One other suggestion I have seen is to search the iMacs Applicstion Folder for a file named Install macOS 11 , double click and file should start. After that I’ll try your Drive DX suggestion.

That was the exact error message. No other suggestions. I will give your suggestion a try.