Big Sur 11.5 Download Failed

I read the responses here about internet speed and connection, but that clearly was not my problem. So I downloaded Big Sur directly from the App Store, and didn't use the "Software Update" feature in settings. That took a while, but it worked fine. Good luck.

Yes, tried this. Same result. Dowloaded over 12 GB (unlike the 2.93 GB update) and then said "Download failed." I have over 900 GB free on my HD, so that's not the issue. Now I am wondering whether trying all these times to download the update, and then the full installer, are leaving fragments behind because my HD space has decreased by about 6 GB and I sure haven't added anything that large to it in the past three days!

I wish that had worked for me. I tried it. Same result as before. Dowloaded over 12 GB (unlike the 2.93 GB update) and then said "Download failed." I have over 900 GB free on my HD, so that's not the issue. Now I am wondering whether trying all these times to download the update, and then the full installer, are leaving fragments behind because my HD space has decreased by about 6 GB and I sure haven't added anything that large to it in the past three days!

Thanks, tried. Received this error message.

Downloading: 100.00%

Failed to download & prepare update: Error Domain=SUMacControllerError Code=7740 "[SUMacControllerErrorPrepareFailed=7740] Failed to perform Prepare operation: [MobileSoftwareUpdateErrorDomain(MSU):MSU_ERR_FILESYSTEM_DOESNT_VERIFY(3)_1_NSPOSIXErrorDomain:92|FullReplacementRequired|]

Just fixed it:

1) Shut down Mac

2) Restart and continue pressing the power button to access startup options

3) select your drive then press & hold the Shift key while clicking " Continue in Safe Mode

4) Log in to your Mac

5) download upgrade and install.

Hello,

Thanks for the command, but the update still can't get through, I get the following error :

Downloading: 100.00%

Failed to download & prepare update: Error Domain=SUMacControllerError Code=7723 "[SUMacControllerErrorPreflightPersonalizeFailed=7723] Failed to perform PreflightPersonalize operation: [MobileSoftwareUpdateErrorDomain(MSU):1256]" UserInfo={NSUnderlyingError=0x157809e50 {Error Domain=MobileSoftwareUpdateErrorDomain Code=1256 "Failed to find SFR recovery volume" UserInfo={NSDebugDescription=Failed to find SFR recovery volume}}, SUMacControllerErrorIndicationsMask=0, NSDebugDescription=[SUMacControllerErrorPreflightPersonalizeFailed=7723] Failed to perform PreflightPersonalize operation: [MobileSoftwareUpdateErrorDomain(MSU):1256], NSLocalizedDescription=Failed to personalise the software update. Please try again.}

Any idea please on what could be the cause?

Thanks in advance !

Yes, I completed all the remedy fixes and it's still failing.

Have you tried downloading Big Sur from the App Store and NOT the update tool?

Same issue...strong internet but download keeps failing. Come on Apple this is your problem

Big Sur 11.5 is a failure to download. Simply does not work.

Check your disc space.

i found that deleting several videos I’d saved created adequate space for the download.

Useful as a second step - but I'd suggest others make sure you have 15GB-20GB of available disk space first!

Yes, its memory issue. I also removed few apps to free memory and installed successfully.

Although i had 100 GB plus free memory.

Thanks,

Amul

I finally got it to work by downloading Big Sur from the App Store, not using "Software Update" like I normally do. I hope this works for you.

I finally got it to work by downloading Big Sur from the App Store, not using "Software Update" like I normally do. I hope this works for you. Good luck.