Unable to update to macOS 27 beta on M3 Macbook

macos tips
1

I’m running on an M3 MacBook Air 13 inch and planned to update to the latest macos 27 beta. After the download completed, a pop-up appeared with the following message:

“Failed to prepare the software update. An error occurred while downloading the selected updates. Please check your internet connection and try again.”

I then had to restart the entire process, only to encounter the same error again.

To troubleshoot the issue, I tried the following steps:

  • Turned off my VPN, but the problem persisted.
  • Re-enabled System Integrity Protection (SIP) using csrutil enable and confirmed that full protection was enabled for Macintosh HD.
  • Booted the Mac into Safe Mode and attempted the update again, but the same error occurred.

Do you guys encounter the same case? How to fix this issue?

2

If you’ve previously disabled System Integrity Protection (SIP) for things like kernel extensions or other system modifications, that may be what’s preventing the update from installing. Unfortunately, macOS doesn’t indicate this directly—it simply displays a misleading network error.

Here are my steps to enable SIP on my mac:

  1. Shut down your Mac completely.
  2. Press and hold the power button until “Loading startup options” appears, then release it.
  3. Select Options, then click Continue to enter macOS Recovery.
  4. From the menu bar, choose Utilities → Terminal.
  5. Type csrutil enable and press Return.
  6. Restart your Mac and try installing the update again.

Hope it works for you

3

Thank you for your suggestions. Unfortunately, tried that but still nothing. I wonder if I should change Security Policy to Full Security?

4

Yes, you can try. Boot into Recovery Mode to change settings to Full Security. After that, rebootyour mac to try again

5

Still nothing changed. I was bothered now, giving up upgrading…

6

I had lots of problems installing beta 27.0 via Software Update, so I recommend downloading the full installer .pkg file (roughly 15.9gb) from Apple server or creating a macOS 27 beta bootable usb installer using a professional Mac disk manager tool like iBoysoft DiskGeeker for Mac without the annoying troubles.