softwareupdate stalls forever

Part Two — macOS Software Update: Further troubleshooting and corrective actions

This section continues the investigation described in Part One.

4. Test whether the network is responsible

Temporarily disconnect any VPN, proxy, DNS filtering, or network security software.

Try downloading over a different network, preferably a mobile hotspot.

Then execute:

softwareupdate --fetch-full-installer --full-installer-version 27.2

If it works over the alternative network, the original network environment is likely interfering with Apple's download services.

Apple's troubleshooting guidance:

If an error occurred while updating or installing macOS

5. Try Safe Mode if the problem persists

On your M1 Mac, shut down and hold the power button until startup options appear.

Select your startup volume, hold Shift, and select Continue in Safe Mode.

Then retry:

softwareupdate --fetch-full-installer --full-installer-version 27.2

If it succeeds in Safe Mode, investigate third-party security software, network filters, and background services.

If normal installation continues failing, Apple also documents reinstalling macOS through Recovery:

How to reinstall macOS – Apple Support

6. You don't need to install 26.6.1 before 27.2

If your objective is to upgrade directly to macOS 27.2, you can request its full installer without installing 26.6.1 first:

softwareupdate --fetch-full-installer --full-installer-version 27.2

This downloads the installer into /Applications; it does not perform the actual upgrade.

Apple documentation:

How to download and install macOS

7. Recommended next diagnostic steps

Before deleting update caches, resetting system services, or reinstalling macOS, I would first establish the following:

softwareupdate --list

profiles status -type enrollment

log show --last 2h \

  --style compact \

  --predicate 'process == "osinstallersetupd"' \

  | grep -Ei 'error|failed|timeout|stall|download|network|brain'

Also establish whether the Mac is personally owned and unmanaged, or enrolled in an organization's MDM (Jamf, Intune, Kandji, Mosyle, etc.).

Conclusion: The full-installer catalog is accessible, but we haven't established whether the normal OTA update service is functioning correctly. The repeated 10% progress messages suggest a problem during installer preparation or downloading, but aren't sufficient to identify its cause.

I recommend investigating those two areas before attempting destructive cache cleanup or modifying system services.

If you are not offered an update in System Settings and/or are unable to install an update downloaded via Terminal, then is likely that you are in Low data mode. Users have reported difficulty upgrading macOS over Wi-Fi in Low data mode, and that toggling that setting OFF enables them to perform a Software Update. 

Turn off Low data mode

• Open System Settings 
• Click on Wi-Fi
• Click on the Details button on the right side of your connected network
• Toggle the setting off

More info from Apple: Wi-Fi settings on Mac - Apple Support

Also note that it has been reported that if the update attempts to install but fails before completing, and your Mac stays on the previous version of macOS, that if you are in Lockdown Mode than disabling that will allow the update to install normally. However, I suspect the simple step of turning off Low data mode is all that you need to do.

The following reply is structured keeps Part One focused on the problem and initial diagnostics, with Part Two covering troubleshooting and corrective actions.

Part One — macOS Software Update fails to detect upgrades and full installer hangs at 10%

Your diagnostics suggest two potentially separate issues: Software Update isn't offering newer macOS versions, and the full-installer download gets stuck during DOWNLOADING_UPDATE_BRAIN.

Your Mac is running macOS 26.6 (build 25G72) on Apple Silicon (M1).

Importantly, softwareupdate --list-full-installers successfully identifies macOS 26.6.1 and 27.2. This confirms that Apple's full-installer catalog is accessible, but does not establish that the normal OTA update service is offering those versions.

1. Why doesn't Software Update show the upgrades?

These commands perform different functions:

softwareupdate --list

Checks for updates applicable to your current installation.

softwareupdate --list-full-installers

Lists available full macOS installers.

Consequently, the two commands can return different results.

Possible explanations include MDM update deferrals, beta-update channel settings, inconsistent Software Update state, or problems communicating with Apple's update service.

First, execute:

softwareupdate --list

softwareupdate --schedule

profiles status -type enrollment

If your Mac is managed, update deferrals are particularly worth investigating.

Apple documentation:

Software Update settings – Apple Platform Deployment

2. Why does the installer remain at 10%?

Your log shows:

osinstallersetupd[3023]:

Progress: phase:DOWNLOADING_UPDATE_BRAIN

stalled:NO

portionComplete:0.100000

estimatedTimeRemaining:-1.000000

This indicates that the installer is in its update-brain download phase.

Importantly, stalled:NO does not guarantee that data is actually transferring. It only means the progress reporter has not classified the operation as stalled.

Likewise, estimatedTimeRemaining:-1 means no remaining-time estimate is available.

If the percentage remains at exactly 10% for hours, I would investigate the download pipeline, particularly network connectivity, Apple's CDN, TLS/proxy interference, incomplete download state, and installer-service errors.

3. Collect the relevant diagnostics

Check available storage:

df -H /

Inspect installer-related logs:

log show --last 2h \

  --style compact \

  --predicate 'process == "osinstallersetupd"' \

  | grep -Ei 'error|failed|timeout|stall|download|network|brain'

Also inspect Apple's Software Update service:

log show --last 2h \

  --style compact \

  --predicate 'process == "softwareupdated"' \

  | grep -Ei 'error|failed|timeout|stall|download|network'

Look for HTTP errors, connection timeouts, TLS failures, repeated download attempts, and asset verification errors.

These messages are much more useful than repeated 10% progress messages.

Continue to Part Two for network troubleshooting, Safe Mode, direct installation of macOS 27.2, and the recommended next steps.

sree_va wrote:

Why Software Update doesn't show any upgrades available from 26.6.1 to 27.2 at all ?

Do you say what exact Mac is this...?

It can take some time for the >System Settings>General>Software Update to present itself...

if applicable.

I never did get the update for 26.7.1...

Just 2 days ago did 26.7.2 present itself on my computer — this is more than a month & half since it dropped Sept 15th.