How to Downgrade the MacOS System (2025 Version)

Overview

Today, I upgraded my Mac to the latest macOS beta. Unfortunately, the beta version had compatibility issues with several tools and workflows I rely on. As a result, I decided to revert to the stable release. However, macOS doesn’t support downgrading across major versions directly, so the process requires performing an erase install followed by restoring your data using Migration Assistant.

This process can be buggy and time-consuming, so I’ve documented some tips and advice that I hope will help others in the same situation.

Note: This guide assumes you’re using a Mac with Apple Silicon.

Before Upgrading (Hopefully You Already Did This)

1. Create a Time Machine backup of your system. It’s essential to back up your data before upgrading across major macOS versions.
2. Disable Time Machine backups after the initial backup and before upgrading. Re-enable it only once you’re confident the beta is stable and you won’t need to downgrade.
   • Why? If your Time Machine creates a backup on the newer macOS version, Migration Assistant won’t let you restore it after downgrading. There is a workaround for this (explained below), but it’s not ideal.

If You Need to Downgrade

If you find that the beta is unstable and want to revert to the previous stable macOS version:

1. Create a bootable installer for your preferred macOS version by following Apple’s official instructions.
2. Perform an erase install:
   • Shut down your Mac.
   • Press and hold the power button until startup options appear.
   • Select the bootable installer.
   • From the top menu bar, choose Recovery Assistant > Erase Mac.
   • Once the Mac is erased, proceed with installing the older macOS.

Restoring from Time Machine Backup

After installing the older macOS version, you can restore your data using Migration Assistant. While this is usually straightforward, a few issues may arise:

1. Incompatible Backups: If your most recent Time Machine backup was made on the newer macOS version, the “Continue” button in Migration Assistant will be grayed out:

   • Workaround: Manually mount the Time Machine volume and delete the backup folders created under the newer version.
   • Caution: After doing this, macOS may have trouble reconnecting to your NAS. A full restart might be necessary to restore proper connectivity.

2. NAS Volume Mount Failure: If you’re restoring from a NAS, Migration Assistant may fail to mount the volume with a vague “Mount Failed” error.

   • Workaround: Mount the Time Machine share manually using Finder or mount before launching Migration Assistant.