Last updated on 2026-07-22

Since around July 14, 2026, we have received many inquiries regarding Microsoft Office on Mac suddenly becoming unavailable. Users have reported seeing an "Unknown Error (Error code: 0x0)" or "Unable to connect to the licensing helper" when attempting to activate their license.

While the exact cause is currently under investigation, please check the recommended requirements and try the following troubleshooting steps in order.
Note (Update): This issue is most likely caused by the expiration of the digital certificate (expired on July 13) used for Microsoft 365 Apps license activation.

1. Check macOS and Office App Versions
   Recently (since July 13), the "minimum version requirements" for Microsoft 365 to function correctly have been updated. First, please ensure your system meets the following conditions:

   • OS: macOS 12 (Monterey) or later
   • Office App Version: "16.83" or later

   Details (Microsoft Official): https://learn.microsoft.com/en-us/microsoft-365-apps/mac/certificate-update-mac-ios#minimum-os-version-requirements

2. Reset the License Helper (If version requirements are met)
   If the issue persists despite meeting the version requirements above, there may be a problem with the "License Helper" running in the background.
   Please try resetting the License Helper using the following steps.

   🔧 How to Reset the License Helper (Mac)

   [Preparation] Open Terminal
   Open "Spotlight Search" (the magnifying glass icon in the top right corner of your Mac screen), type "Terminal", and launch the app with the black icon.

   [STEP 1] Gain Administrator (root) Privileges
   1. Paste the following command into Terminal and press the Return (Enter) key.

   sudo -s

   2. It will prompt you with Password:. Enter your Mac login password and press the Return (Enter) key.

   ⚠️ Note: When you type your password, characters (like "*") or cursor movement will NOT be displayed on the screen. This is a normal security feature. Just type your password completely and press Enter.

   *If the prompt changes to root#, you have successfully switched to administrator privileges.

   [STEP 2] Re-register the Authentication System (License Helper)
   Try [Pattern A] first. If it fails (returns an error), try [Pattern B] which is for newer macOS versions.
   *Please copy and paste the commands one line at a time, pressing the Return key after each line.

   ▶ Pattern A (Standard Mac)

   1. Unload the old registration:

      launchctl unload /Library/LaunchDaemons/com.microsoft.office.licensingV2.helper.plist

   2. Load a new registration:

      launchctl load -w /Library/LaunchDaemons/com.microsoft.office.licensingV2.helper.plist

   ▶ Pattern B (If Pattern A returns an error on latest macOS)

   1. Force unload the old registration:

      launchctl bootout system /Library/LaunchDaemons/com.microsoft.office.licensingV2.helper.plist

   2. Bootstrap a new registration:

      launchctl bootstrap system /Library/LaunchDaemons/com.microsoft.office.licensingV2.helper.plist

   [STEP 3] Grant Correct Execution Permissions
   Paste the following command and press the Return (Enter) key.

   chmod 4755 /Library/PrivilegedHelperTools/com.microsoft.office.licensingV2.helper

   This completes all Terminal operations. You can now close the Terminal app.

   [STEP 4] Verification
   Launch an Office app like Excel or Word and check if you can sign in (activate your license) normally.

3. Reinstall Microsoft 365
   ⚠️ Important Note Before Proceeding (Check your macOS version)
   Reinstallation Requirements: The system requirement for macOS is the "three most recent versions." As of July 17, 2026, you will NOT be able to reinstall Office unless you are using macOS 14 (Sonoma) or later.
   Difference from the requirement in "1.": The "macOS 12 (Monterey) or later" mentioned earlier is the minimum requirement to avoid Reduced Functionality Mode if Office is already installed.
   *If your macOS is older than 14, please be aware that once you uninstall Office, you will not be able to get it back. Please check your version beforehand.
   
   Follow the official Microsoft guide below to uninstall Office.
   https://support.microsoft.com/en-us/office/uninstall-office-for-mac-eefa1199-5b58-43af-8a3d-b73dc1a8cae3
   
   Once uninstallation is complete, please refer to the user manual to reinstall it.
   https://www.iimc.kyoto-u.ac.jp/en/services/cloud-service/microsoft#03