Can’t Install macOS Sequoia 15.4 on Mac? You’re Not Alone — Here’s What to Do

Trying to install macOS Sequoia 15.4 and running into endless issues? You’re definitely not the only one. A growing number of Mac users, especially those with M1, M2, and M3 chips, are reporting failed updates, boot loops, and vague errors — or no error at all.

You may receive error messages like Updates Not Installed or Installation Failed.

If you’re stuck, here’s a breakdown of what’s happening and several fixes that have worked for others, including me.

It appears that users trying to update from macOS 15.3 to 15.4 are seeing a variety of problems:

• GUI method (System Settings): Prompts for your password twice, then gives a generic error.
• Terminal method (softwareupdate): Asks for a password, appears to start, then exits silently — even with —verbose.
• Installer download fails partway, or downloads macOS Sonoma instead.
• Some users ended up in an infinite boot loop, having to reinstall the OS from scratch.

Fixes:

1. Download and Launch the Full Installer Manually

It seems that this fix helped multiple users break through the failed update loop.

Steps:

1. Open Terminal.
2. Run the following command:

   sudo softwareupdate --fetch-full-installer -a --launch-installer -R

3. This will download the full installer to your /Applications folder and automatically launch it.
4. Once you see the installer open, select your disk and let it start, wait a minute until the progress bar appears.
5. You can cancel the installation, go back to System Settings > General > Software Update, and retry the update. You should now be prompted to accept the Terms and Conditions, and the download should start correctly.

Alternate Version (Specific to 15.4)
If you want to ensure you’re downloading version 15.4, try:

sudo softwareupdate --fetch-full-installer --full-installer-version 15.4

2. Reboot into Safe Mode and Try Again

Some users reported that Safe Mode helped the update go through.

Steps:

1. Shut down your Mac.
2. Press and hold the Power button until you see “Loading startup options.”
3. Hold the Shift key, then select your startup disk.
4. Click Continue in Safe Mode.
5. Once booted, go to System Settings > Software Update and try again.

3. Check System Integrity Protection (SIP)

Some power users checked to see if SIP was interfering.

Steps:

1. Open Terminal.
2. Run:

   csrutil status

3. It should say: System Integrity Protection status: enabled.

Even though SIP didn’t seem to be the root cause for most, knowing its status helps with deeper troubleshooting — especially on corporate-managed Macs.

4. Ensure You Have Enough Disk Space

Apple’s updates need free space to unpack and install.

Double-check:

• Go to Apple Menu > About This Mac > Storage.
• Aim for at least 25-30 GB free, even if the update size is smaller.

It is easy to free up space.

5. Try Again Later

A few users found the issue magically disappeared after a day or two.

It’s possible Apple was gradually pushing the full installer to its servers, and the update failed earlier due to incomplete packages.

Apple’s servers may have been overloaded or temporarily unavailable, preventing the update from downloading properly. In some cases, simply waiting and trying again later has resolved the issue. You can easily check Apple’s system status.