Fix REGDB_E_READREGDB 0X80040150: Registry Read Failure

Cause 1: Corrupted or missing registry key after a failed Office update

You'll see this error most often right after a Windows update or an Office repair that didn't complete. The registry key that Outlook or another Office app needs is either missing or has bad data. The fix is to rebuild that key using the Office installation itself.

Fix: Run Office Repair (Quick and Online)

1. Close all Office apps – Outlook, Word, Excel, all of them.
2. Press Windows + R, type appwiz.cpl and press Enter. This opens Programs and Features.
3. Find your Office version (e.g., Microsoft 365, Office 2019). Right-click it and select Change.
4. Choose Quick Repair first. Click Repair. If you're prompted by User Account Control, click Yes.
5. Wait for the repair to finish. You'll see a progress bar. After it finishes, you'll get a message that says "Repair complete" – don't ignore it. Click Close.
6. Now try to open Outlook again. If the error persists, repeat the process but this time choose Online Repair – it takes longer but is more thorough.

What to expect: After Quick Repair, the registry keys are rebuilt automatically. You should be able to open Outlook without the error. If you still see 0X80040150, move to cause 2.

Cause 2: The registry key exists but your account lacks permission to read it

This happens when a previous user account or an old installation left permissions that block your current user. You'll see the error in Outlook, but also in Access or even during Office activation. The registry key is there, but Windows won't let you read it.

Fix: Take ownership and grant full control

1. Press Windows + R, type regedit and press Enter. Click Yes if prompted.
2. Navigate to this path – you can paste it into the address bar:

   HKEY_CURRENT_USER\Software\Microsoft\Office\16.0

   If you're on Office 2013, use 15.0. For 2010, use 14.0.

3. Right-click the 16.0 (or your version) folder and select Permissions.
4. In the Permissions dialog, click Advanced.
5. At the top, next to Owner, click Change.
6. Type your Windows username, click Check Names (it underlines the name), then OK.
7. Check the box that says Replace owner on subcontainers and objects, then click Apply and OK.
8. Back in the Permissions window, make sure your username has Full Control checked. If not, check it and click Apply.
9. Close the Registry Editor and restart Outlook.

What to expect: After you take ownership, Windows lets you read the keys. The error should disappear. If it doesn't, you're dealing with a deeper corruption – go to cause 3.

Cause 3: Damaged Outlook profile or MAPI keys

If the error shows only in Outlook (not other Office apps), it's likely your Outlook profile's registry entries are broken. This happens when Outlook crashes mid-write or a sync tool messes with the profile keys.

Fix: Create a new Outlook profile

1. Close Outlook completely.
2. Go to Control Panel > Mail (search for "Mail" in the Start menu).
3. Click Show Profiles.
4. Select your current profile and click Remove. Yes, it deletes the profile, but your emails are on the server – you won't lose them.
5. Click Add. Give it a name like "NewProfile" and click OK.
6. Follow the prompts to set up your email account. You'll need your email address and password.
7. Once set up, open Outlook. It might take a few minutes to sync.

What to expect: Outlook creates fresh registry entries for the new profile. The error should be gone. If you have to reconfigure your email, that's the trade-off – but it beats the error.

Quick-Reference Summary

Start with the first fix because it addresses the most common trigger – a botched update. If you're short on time, the registry permission fix is the fastest and often works. The profile recreation is the nuclear option, but it's the closest to a guaranteed fix if the others fail.