How to Fix 'Bad File Name or Number' Error in Microsoft Access Wizards
Question details
Users need to resolve an issue where built-in Access tools fail to launch due to a missing or corrupted system file.
- Product
- Microsoft Access
- Device & OS
- Windows
- Scenario
- Attempting to open the Input Mask Wizard, Lookup Wizard, or Database Documenter within an Access database.
- Observed behavior
- A 'Bad file name or number' error message appears, preventing the requested wizard from opening.
Ensure you have administrator privileges on your Windows computer, as modifying Microsoft Office installations requires elevated permissions. Additionally, enable 'Show hidden files and folders' in Windows File Explorer to verify system directories.
Repair the Microsoft Office Installation
Running the built-in Office repair tool can automatically detect and replace missing or corrupted Access files like ACWZUSR12.ACCDU.
The most common cause of the wizard error is a corrupted Access installation. Using the native repair tool replaces missing system files without affecting your personal databases.
Press the Windows key, type 'Control Panel' in the search bar, and hit Enter.
Click on 'Programs' and then select 'Programs and Features'.
Scroll down to find Microsoft Office or Microsoft 365 in the list, right-click it, and select 'Change'.
Select 'Quick Repair' and click 'Repair'. Wait for the process to finish, then restart your computer and open Microsoft Access to test the wizard.
Verify the ACWZUSR12.ACCDU File Location
Manually checking the hidden AppData folder helps confirm whether the critical wizard file is actually missing or misplaced.
Reinstall Microsoft Office
If repairing the installation fails to restore the missing wizard files, completely reinstalling the software is required.
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Frequently Asked Questions
Why does the 'Bad file name or number' error only happen in specific Access wizards?
Tools like the Input Mask Wizard, Lookup Wizard, and Database Documenter rely on a specific add-in file named ACWZUSR12.ACCDU. If this specific file is deleted, misplaced, or corrupted, core database functions will still work, but the dependent wizards will fail to launch.
Can I simply copy the missing ACWZUSR12.ACCDU file from another computer?
Yes. If you have access to another PC running the exact same version of Microsoft Access, copying the ACWZUSR12.ACCDU file into your C:\Users\<username>\AppData\Roaming\Microsoft\Access\ folder can often resolve the issue without requiring a full reinstallation.
Why can't I find the AppData folder in my user directory?
By default, Windows hides the AppData folder to protect critical system and application files from accidental deletion. You must open File Explorer, go to the View tab, and check 'Hidden items' to make the folder visible.
