Fix COM Registration Errors

How to resolve COM registration errors when installing or updating OfficeConnect.

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COM registration errors usually surface during a Workday OfficeConnect install or upgrade and point to a broken Microsoft Office add-in registration. Confirm your machine meets the system requirements before working through the fixes — multiple Office versions installed side by side is the most common root cause.

Symptom: You receive an error like the following when trying to install or update OfficeConnect:

System.InvalidCastException: Unable to cast COM object of type 'System.__ComObject'
to interface type 'Microsoft.Office.Core.IRibbonUI'.

Why this happens

OfficeConnect is an Excel COM add-in that relies on Excel objects registered correctly by your Microsoft Office installation. This error occurs when:

Excel’s COM objects aren’t registered correctly
You have multiple versions of Microsoft Office installed (e.g., Project 2016 and Excel 2013), leading to conflicting versions of the MS-VSTO library

Fix option 1: Repair Microsoft Office

Many users resolve this by repairing the Office installation:

Open Windows Settings Go to Start → Settings → Apps & Features.

Find Microsoft Office and click Modify Select Microsoft Office from the list and click Modify.

Choose Online Repair Select Online Repair (not Quick Repair) and click Repair. This fully reinstalls Office components and re-registers COM objects.

Try installing OfficeConnect again After the repair completes, run the OfficeConnect installer again.

Fix option 2: Registry key correction

If the repair doesn’t work, the troubleshooting tool will identify the specific registry key causing the problem. Your IT department can make adjustments to the registry keys listed in the tool’s output.

See Run the Troubleshooting Tool to generate a diagnostic log.

Fix option 3: Disable conflicting add-ins

Open Excel and go to Options File → Options → Add-Ins.

Change Manage to COM Add-ins and click Go This shows all active COM add-ins.

Uncheck all add-ins except Adaptive Planning for Excel Click OK, then close and reopen Excel.

Try signing in to OfficeConnect If this resolves the issue, re-enable add-ins one at a time to identify the conflict.

Next steps

Resolve OfficeConnect Update Errors if the issue only appears during version updates
Run the troubleshooting tool to capture the exact registry keys at fault
Install as an IT Admin to redeploy a clean per-machine installation across users

Last modified May 19, 2026: Rename 'Get Started' section to 'Wiki' site-wide (6ebea16d)