How To Update Macos High Sierra 10.13.6 To 10.15 - Verified
How to upgrade macOS High Sierra (10.13.6) → macOS Catalina (10.15)
This guide assumes you’re running 10.13.6 and want to move to 10.15 (Catalina). It’s prescriptive and steps are ordered for safety and success.
Before you begin — checklist
- Compatibility: macOS Catalina supports these models: MacBook (Early 2015 or later), MacBook Air (Mid 2012 or later), MacBook Pro (Mid 2012 or later), Mac mini (Late 2012 or later), iMac (Late 2012 or later), iMac Pro (2017), Mac Pro (Late 2013 and some mid-2010/2012 models with recommended GPU). If your Mac is older than those, Catalina won’t install.
- 64-bit apps only: Catalina runs only 64-bit apps. Identify 32-bit apps via Apple menu > About This Mac > System Report > Applications; any app marked “No” in the 64-bit column will stop working after the upgrade.
- Free disk space: Aim for at least 20–30 GB free (installer + temporary files).
- Backup: Make a full backup (Time Machine or bootable clone). Do not skip this.
- Verify hardware and software compatibility
- Click Apple menu > About This Mac to get model/year and current free storage.
- Use System Report > Software > Applications to list 32-bit apps. Note replacements or updates you’ll need.
- Update High Sierra fully
- Apple menu > App Store > Updates: install all available updates for 10.13.6 (firmware and app updates) before upgrading.
- Backup your Mac
- Time Machine: connect an external drive and run a full backup (System Preferences > Time Machine).
- Optional: Create a bootable clone with Carbon Copy Cloner or SuperDuper for faster recovery.
- Free up space and tidy apps
- Remove unused apps and large files.
- Empty Trash and reboot.
- Download macOS Catalina (10.15)
- Open the App Store and search for “macOS Catalina” (if not available, use this direct method: visit Apple’s support page for macOS Catalina and follow the link to the App Store).
- Click Get / Download. The installer (~8–9 GB) will download to /Applications as “Install macOS Catalina.”
- Prepare installers and peripherals
- If you prefer a clean install or need to upgrade multiple Macs, create a bootable USB installer (16 GB USB drive):
- Run the installer (upgrade in-place)
- With the Catalina installer in /Applications, double-click it and follow prompts.
- The Mac will restart multiple times. Allow the process to complete (30–90 minutes depending on machine).
- Post-upgrade steps
- Sign in with your Apple ID when prompted.
- Open System Preferences > Software Update to install any post-install updates.
- Reinstall or update apps that were 32-bit (find 64-bit versions or alternatives).
- Check peripherals (printers, scanners); install updated drivers if needed.
- Verify Time Machine and other backups are working.
- Troubleshooting
- Installer won’t start: re-download the installer from the App Store.
- Not enough space: remove large files or create a larger free partition.
- Boot issues after install: boot into Recovery (hold Command-R at startup) and use Disk Utility First Aid or reinstall macOS from Recovery.
- If downgrade needed: restore from your Time Machine backup or clone.
- Alternative: Upgrade path to newer macOS
- Apple allows skipping versions, but hardware support limits apply. If your Mac supports later versions (Big Sur, Monterey, Ventura), consider upgrading to the newest supported release — check Apple’s compatibility pages and backup first.
Summary checklist (quick)
- Confirm model compatibility
- Identify 32-bit apps and plan replacements
- Backup (Time Machine or clone)
- Free ≥20–30 GB disk space
- Download Catalina from App Store or create USB installer
- Run installer, follow prompts, wait for completion
- Update apps/drivers and verify backups
If you want, I can provide:
- A one-click Terminal command for creating a Catalina USB installer (tell me the USB volume name), or
- A short list of common 32-bit apps and modern replacements.
To update from macOS High Sierra 10.13.6 to macOS Catalina 10.15, you must first confirm your hardware is compatible. If it is, you can download the installer directly from the Mac App Store. 1. Check Hardware Compatibility
Your Mac must be one of the following models to officially run macOS Catalina: MacBook: Early 2015 or newer MacBook Air: Mid 2012 or newer MacBook Pro: Mid 2012 or newer Mac mini: Late 2012 or newer iMac: Late 2012 or newer iMac Pro: 2017 or newer Mac Pro: Late 2013 or newer 2. Prepare for the Update
Back up your data: Use Time Machine to back up your Mac before starting. how to update macos high sierra 10.13.6 to 10.15
Check 32-bit apps: Catalina does not support 32-bit apps. Many older programs (like older versions of Microsoft Office or Adobe CS6) will stop working.
Free up space: You need at least 15–20 GB of available storage.
Check internet: Ensure you have a stable broadband connection for the 8 GB download. 3. Download and Install
Since 10.13.6 is an older version, the update will not appear in "Software Update." You must use the App Store. Open the macOS Catalina page in the Mac App Store. Click Get or Download.
The Software Update window in System Preferences will open; click Download again.
Once the download finishes, the installer will open automatically. How to upgrade macOS High Sierra (10
Click Continue and follow the on-screen instructions to complete the installation.
For a step-by-step walkthrough of the entire upgrade process: How to Upgrade to Catalina Mac OS X 10.15 Gemsbok Apple Tips and Tricks YouTube• Dec 4, 2019 Troubleshooting & Tips macOS - How to Upgrade - Apple (SI)
Moving Forward: How to Upgrade from High Sierra (10.13.6) to macOS Catalina (10.15)
Upgrading from macOS High Sierra 10.13.6 to macOS Catalina 10.15 is a significant jump. It moves your Mac into a modern era of features like Apple TV, Podcasts, and enhanced security, but it also marks the end of support for older 32-bit apps. Follow this guide to ensure a smooth transition. Step 1: Check Compatibility
Before you start, verify that your Mac hardware is officially supported. Catalina generally supports most Macs from 2012 onwards. Apple Support How to Update Mac to 10.15: A Step-by-Step Guide
Step 3: Obtain the macOS Catalina Installer
Apple removed Catalina’s direct download page from the App Store front page, but the installer is still available. Verify hardware and software compatibility
Method 1: Via the App Store link
Method 2: If the App Store fails
- Older Macs sometimes get stuck on “Requesting.” In that case, use a web browser to download from Apple’s support site or use
gibMacOS tool (advanced). But first, try Method 1 on a good Wi-Fi connection.
Technical Procedure: Upgrading from macOS High Sierra 10.13.6 to macOS Catalina 10.15
Date: October 26, 2023
Subject: System Upgrade Path and Migration Strategy
Target Audience: Mac Users, System Administrators, and IT Support Staff
Method 3: Using softwareupdate Terminal command (if available)
softwareupdate --list-full-installers
softwareupdate --fetch-full-installer --full-installer-version 10.15.7
⚠️ Before You Begin: The 32-Bit Warning
This is the most important change between High Sierra and Catalina. macOS Catalina does not support 32-bit applications.
Before updating, check if you rely on older software (like older versions of Photoshop, Microsoft Office 2011, or some music production software). If you have 32-bit apps you cannot live without, they will stop working after you update. You can check your apps by going to the Apple Menu > About This Mac > System Report > Applications and looking at the "64-bit" column.