Outlook COM Error

Owned by Paul Hitchcock
Mar 17, 2023
3 min read

Issue

When interacting with Outlook an error windows is displayed with the following message

Unable to cast COM object of type 'Microsoft.Office.Interop.Outlook.ApplicationClass' to interface type 'Microsoft.Office.Interop.Outlook._Application'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{00063001-0000-0000-C000-000000000046}' failed due to the following error: Interface not registered (Exception from HRESULT: 0x80040155)

This error is indicating that the reference to Outlook cannot be found

Reason

This is typically caused by one of the following

  • Outlook is not installed on the PC

  • Outlook has left over registry entries from a software upgrade

  • Crows Nest and Outlook are not running with the same bit (32bit vs 4 bit)

Registry Entries

Registry entries may be left behind when installing a new version of Outlook over an older version

MS Office Repair

Usually a Full Online Repair of Office will typically fix the registry issues

  1. Right-click the Windows Start Button

  2. Open “Apps and Features”

  3. Find and select “Microsoft 365 Apps for Business” (or similar MS Office product) and click “Modify”

  4. Select “Online Repair” and wait for it to complete.
    The ‘Quick Repair’ will not fix this issue, it will only look to repair missing or damaged files



Manual Registry Check

Below are steps for manually checking the registry for advanced users if the Office Online Repair does not work.

  1. Open “Registry Editor” from the Start Menu

  2. Navigate to the following location:

    • HKEY_CLASSES_ROOT

      • Typelib

        • {0006F062-0000-0000-C000-000000000046}

  3. Expand {0006F062-0000-0000-C000-000000000046} verify there is only be a single sub key. If there are more than one, the extras should be deleted. Review the contents to decide which folders should be removed.

 

32 bit vs. 64 bit

To see which version of Crows Nest you are running

Prior to version 2023-02-09, Crows Nest only had a 32bit version

Version 2023-02-09 and later, Crows Nest installs both a 32 and 64 bit version. Running the app named “Crows Nest” will open the 64 bit version, opening the app named “Crows Nest 32 bit” will open the 32 bit version. The 32 bit version will have the added text “(32 bit)” in the title of the login and main client window.

 

To see which version of Outlook you have installed

  1. Open Outlook

  2. Click on “File” then “Office Account”

  3. Click on “About Outlook”

  4. See the text at the of the version at the top of the About window