Hello dchu,
Thank you for posting on Microsoft Q&A forumAdd to Dictionary only succeeds when Word can write to the default custom dictionary and the dictionary’s language association and location/permissions are valid. If the default dictionary is missing, unchecked, set to an incompatible language then the right‑click adds silently fail and the red wavy underline remains.
Here are some troubleshoot steps you can try to see if it fixes the "add to dictionary" issue.
First, let's ensure the correct dictionary is active and not set to read-only.
- In Word app, go to File > Options.
- Select Proofing from the left-hand menu.
- Click the Custom Dictionaries... button.
- In the dialog box, make sure that CUSTOM.DIC (Default) is checked.
- Select CUSTOM.DIC and check its file path listed below. Ensure the folder it's in is not in a read-only location (like a network drive you don't have write permissions for).
If the default dictionary file is corrupted, the easiest fix is to create a new one and set it as the default.
- Follow steps 1-3 from the solution above to open the Custom Dictionaries dialog.
- Click the New... button.
- Give the new dictionary a file name (e.g., MyDictionary) and click Save.
- A new dictionary will appear in your list. Make sure it is checked, then select it and click Set as default.
- Click OK to close all dialogs. Now, try adding a new word again.
If the steps above do not work, the issue may be with your Office installation. A quick repair or online repair often resolves these kinds of problems. Refer to this site on how to do it:
https://support.microsoft.com/en-us/office/repair-an-office-application-7821d4b6-7c1d-4205-aa0e-a6b40c5bb88b
Feel free to reply back to this post if you need further assistance, I'll be happy to help.
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