Quick answer
When a macOS update freezes halfway, the most common cause is insufficient disk space, an unstable connection or an interrupted installation process. First wait 20 to 30 minutes, then check disk space and network and restart your Mac. If the problem persists, run the installation from Safe Mode or via Recovery Mode, after making a backup.
How to recognize the problem
- Progress bar stays in the same place for more than 20 minutes
- Mac restarts in a loop and shows the Apple logo again
- A message appears saying the update cannot be installed
- After restart, the system is still on the old macOS version
- Installation fails at the end, during the final restart
Most common causes
Not enough disk space
The macOS installer requires several tens of gigabytes of free space, and if there isn't enough, the process stops without a clear message.
Interrupted or slow internet connection
If the download is interrupted, the installer waits for parts of the package that never arrive and the progress bar freezes.
Corrupted downloaded installer
A partially downloaded or corrupted package prevents the installation from starting or finishing.
Problem with Apple services or certificate
A temporary outage of the update verification server can block the check and prevent the installation from continuing.
Interference from other programs or extensions
Antivirus, VPN or system management extensions can block installation processes.
Step-by-step fix
- 1
Wait and do not interrupt the process
Leave your Mac turned on for at least 20 to 30 minutes. During installation, the progress bar often stays in one place while files are being prepared, so interrupting can cause more harm than waiting. If nothing changes after that time, move on to the next step.
- 2
Check free disk space
Open
Apple menu > System Settings > General > Storageand see how much space is free. For a major macOS update, leave at least 30 GB, and preferably more. If space is low, delete unnecessary files or empty the Downloads folder before trying again. - 3
Check the connection and re-download the update
Connect your Mac to a stable Wi-Fi network or, even better, to an Ethernet cable. Open
Apple menu > System Settings > General > Software Update, and if the download is stuck, cancel it and start again. Do not turn off your Mac until the download is complete. - 4
Restart your Mac and try again
Open
Apple menu > Restart. If a dialog appears with an option to reopen windows, that is not mandatory. After the restart, runSoftware Updateagain and let the installation finish without opening other applications. - 5
Run the installation from Safe Mode
Turn off your Mac. On a Mac with Apple silicon, press and hold the power button until startup options appear, select the startup disk, then hold Shift and select Safe Mode. On an Intel Mac, turn on your Mac and immediately hold Shift until the login window appears. In Safe Mode, the system loads only essential components, so the installation often completes without interference. When done, restart your Mac normally.
- 6
Remove the old installer
If an old macOS installer remains in the Applications folder, delete it and empty the Trash. Then re-download the update via
Software Update. This eliminates the possibility of the system using a corrupted package. - 7
Use Recovery Mode as a fallback option
If you don't already have a backup, make one before this step. Turn off your Mac. On a Mac with Apple silicon, press and hold the power button until startup options appear, then select Options. On an Intel Mac, turn on your Mac while holding Command and R until the Apple logo appears. In the Recovery window, select the option to reinstall macOS and follow the instructions. This procedure usually does not erase personal files, but it can take a while.
- 8
Check date and time
An incorrect date can prevent certificate verification during the update. Open
System Settings > General > Date & Timeand enable the option to set date and time automatically via the network. Then run the update check again.
If nothing helps
If the installation keeps failing at the same point, first make a full backup via Time Machine or to an external disk. Then check whether your Mac is connected to a corporate network with a filter that blocks Apple services, as this often happens in offices. As a last resort, you can download the full macOS installer from Apple's website or the App Store and run it manually, but only do this if you have a stable connection and enough space. If your Mac ends up in a restart loop on every attempt, stop the process and contact support, because further attempts can damage the system.
How to prevent it
- Keep at least 30 GB of free space on the system disk
- Update macOS over a stable connection, preferably Ethernet
- Make a Time Machine backup before a major update
- Do not turn off your Mac during download or installation
When to call a professional
If your Mac enters a restart loop, won't boot or reports an installation error even after Recovery Mode, it is better to contact IT support than to continue on your own, because further attempts can endanger your data.
IT infrastructure maintenance · Servers, networks, backup, security and helpdeskFAQ
How long can the progress bar stay before I interrupt the installation?
It is normal for the bar to stay for 20 to 30 minutes, especially on older Macs. If nothing changes after that time and your Mac is unresponsive, you can restart it and try again, but keep in mind that a forced restart during installation can leave the system in an incomplete state.
Will I lose files if I interrupt the update?
Interrupting during installation usually does not erase personal files, but it can leave the system in an incomplete state. That is why it is best to have a backup before any major update.
Why does the update always stop at the same percentage?
Most often it is a corrupted downloaded package or insufficient disk space. Delete the old installer, free up space and download the update again.