Update failed macOS 15.0.1 > 15.1

Problem solved, at least for me. This is how, thanks to the Apple chat support:

1. System settings -> Networks -> Wi-fi: select the network you're logged on
2. Press on "Details"
3. Go to DNS (left hand menu)
4. Change the DNS servers (press on +):
   1. Lign 1: 8.8.8.8
   2. Lign 2: 8.8.4.4
5. Start again the update

And make sure to have no VPN on.

Good luck

Have the same problem. The file is downloaded. Then my MBP starts "preparing" to end up with the same message as above.

Surfing the internet I found only one solution to this issue that actually worked: It requires a second MacBook. Install Apple Configurator on a Mac and connect the Mac to upgrade with USB-C to USB-C cable to configurator. Put the Mac to upgrade in recovery mode (use google to find the 4 finger keyboard combination. Configurator will show DFU as a sign that the Mac is listening. First use "revive" and then install OS. I couldn't apply it, because I've got only one mac.

My Journey inspired by Googling answers(intel MBP I9 2019 1TB)

• reset of caches does not work
• verifying health of startup disk with disk utility does not work
• reset of NVRAM etc, did not work.
• Install from external USB drive did not work
• install from recovery did not work
• install from internet for latest version doesn't work

Same exact issue...please update us when this issue is addressed...I've never had so much trouble installing an OS update on a Mac before...

IP address 8.8.8.8 is Google's DNS server (feel free to look it up), so when you change the Mac's DNS settings for the network you use, you tell the Mac that all name to IP address lookups should happen at 8.8.8.8 or 8.8.4.4. You are not changing settings on your Wifi router, you are overwriting the default settings your Wifi access point has given you're Mac.

I've followed you lead and it works. I am on 15.1 now. Using Google means that there is an issue at DNS level. Somehow connecting to Apple through Google works better then through the DNS settings that are default on the Wifi connection.

I've had the same experience. Setting the DNS servers didn't resolve it for me.

I had my external "Time Machine disk" attached, and my iPhone attached via an USB-C hub while updating.

On the last of my attempts, before starting the update, I decided to remove both the USB-C hub, and all attached devices/disks. This time the update did succeed.

Maybe this helps someone in their troubleshooting process.

Restart in safe mode and try initiating the update again.

Trying my 4th time today, stuck in the preparing then failed again.

I've changed the DNS setting to 8.8.8.8 and 8.8.4.4 in both my MacBook pro and wifi router.

I had the same problem and got it resolved by adding the DNS 8.8.4.4 in wifi. Thank you.

This worked for me.

Same. Completes the download and then progress bar advances to "preparing" stage and then stalls out after about 5-10 minutes. No issue with Internet bandwidth or connectivity on my end...

Safe mode did not help.

Tried all the DNS updates (and a few other suggestions found online) and multiple times throughout the day. Nothing worked for me. I updated 2 family MB Airs without any issues, first time go. My MBP won’t update at all.

DNS was already configured correctly before starting the update, but it took several times to (re)download the update anyway and once dowloaded it did not want to start the updating process several times. On failing, it started downloading again. My Mac now finally gives in. Black screens, every now and then with an apple and progress bar on it, for quite some time. It now estimates the time left to install, although never estimated correctly. Fingers crossed.

The safe mode didn’t help, I am afraid.