Office for Mac Issues

How to Fix Cannot Add Words to Dictionary in Word for Mac 365

Phi Hung Vo Oct 19, 2026 869 views

Question details

Users are unable to add new words to the custom dictionary in Microsoft Word for Mac 365.

How to Fix Cannot Add Words to Dictionary in Word for Mac 365

Product: Microsoft Word for Mac 365
Device & OS: macOS
Scenario: Attempting to add unrecognized custom words to the spelling dictionary so they are not flagged as errors.
Observed behavior: The dictionary feature fails to save or recognize newly added words, often occurring after a recent software update or due to corrupted cache files.

Before you start

Ensure you have saved all your open documents and fully closed all Microsoft Office applications (Word, Excel, PowerPoint, Outlook) before proceeding with cache removal steps.

Solution 1Recommended

Clear Word Cache and Container Folders

Resetting the specific container files on macOS can resolve internal conflicts that prevent the dictionary from saving custom words.

When Word updates to a new version, older container and cache files can sometimes become corrupted. This corruption often leads to issues with application settings, including the custom spell check dictionary. Moving these specific configuration files forces Microsoft Word to recreate clean, default versions upon the next startup.

Access the hidden Library folder

Make sure all Office apps are closed. Open Finder, press Command+Shift+G on your keyboard, type ~/Library in the search bar, and press Return.

Move the Word Container

Inside the Library folder, locate and open the 'Containers' folder. Find the folder named 'Microsoft Word' and drag it to your Mac's desktop to serve as a temporary backup.

Move the Group Container

Navigate back to the main ~/Library folder and open 'Group Containers'. Locate the folder named 'UBF8T346G9.Office' and move it to your desktop as well.

Restart Word and test

Reopen Microsoft Word. The application will take a moment to rebuild its necessary cache files. Type a custom word and try adding it to the dictionary to verify the issue is resolved.

Backup Precaution: Do not permanently delete the UBF8T346G9.Office folder immediately. It may contain your Outlook profiles, signatures, and custom Word templates. Keep it on your desktop until you are sure everything works perfectly.

Solution 2

Verify Custom Dictionary Settings

Check if your custom dictionary is properly selected and configured as the default destination for new words.

Free Microsoft Office alternative

Use WPS Office for a Seamless Mac Experience

If you are tired of dealing with corrupted cache files and updating errors in Microsoft Word for Mac, consider switching to WPS Office. It provides a lightweight, highly compatible, and free alternative with robust spell check and custom dictionary tools built right in.

1. Download and Install: Visit the official WPS website and download the macOS version of WPS Office.
2. Open Your Documents: Launch WPS Writer and seamlessly open your existing .docx files without losing any complex formatting.
3. Manage Custom Dictionary: Navigate to the Review tab, select Spell Check, and effortlessly add your unique terminology to the WPS custom dictionary.

Fully compatible with Microsoft Word (.docx) and other Office formatsLightweight architecture that runs smoothly on all macOS versionsBuilt-in spelling check with an intuitive, glitch-free custom dictionaryFree to download and use with a highly familiar user interface

microsoft office alternative - wps office

Frequently Asked Questions

Why is my custom dictionary not saving new words in Word for Mac?

This commonly happens due to corrupted cache or container files after a macOS or Microsoft Office software update. The application loses the ability to write to the dictionary file, requiring a reset of its container directories.

How do I access the hidden Library folder on a Mac?

To access the hidden Library folder, open Finder, press the shortcut Command+Shift+G, type '~/Library' exactly as shown, and press the Return key.

Will deleting the UBF8T346G9.Office folder delete my documents?

No, it will not delete your saved Word documents (.docx files). However, moving this folder resets Word's preferences and cache, and it may contain Outlook profiles or customized templates, which is why you should back it up to your desktop first rather than deleting it immediately.

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