Guys I think I have a solution.
If you are using MS Office 2007 or below you may come across with this update error.
This is something related to Office File Validation Add-in (KB2501584).
I searched MS support sites for this update but received nothing.
After searching many sources I found "Office File Validation Add-in" published by MicroSoft.
I will provide the link here. after installing this I got 2 more updates and the update error is gone and my system is up to date.
Here's the Link!
MS Office File Validation Add-In
Note: MS Office 2010 users may not require this, I think !
Let me Know if this helped You !
Hello everyone that had or still have the Office File Validation Add-in Error code 0x80240023 (KB2501584).
Today is March 16, 2021, and I've just solved my problem with the Office File Validation Add-in Error.
Since I upgraded to Windows 10 I had never had a problem with this item, but last week I had to restore Windows (I used the 'keep my files & etc.' option) so this problem appeared when I started updating system.
I kept getting this Error code with every Windows Update run, so I searched MS site which offered the 'hide method', but I wanted it fixed so I googled it and among others chose this link FIX: Error 0x80240023 in Windows 10 Update (Solved) • Repair Windows™ which I found very helpful because aside from the said 'hide method' as was suggested somewhere at the beginning of this thread, it offered to install the missing file as a way of handling it, as I was interested in. So I went for option 1 of this link and so far it worked fine. I ran Windows Update twice now and everything is safe & sound on my computer.
I hope this is still helpful for anyone who find their selves in the same situation.
Here is a print-screen of the link's first piece of information. I also pasted a summary of the instructions steps which I printed to make it easier for me.
I hope it helps you!

MY COPY:
Method 1. Install Manually the Microsoft Office File Validation Add-in.
- Open Windows Explorer & navigate to the following folder: C:\Windows\SoftwareDistribution
- In the search bar type OFV.CAB and press Enter.
3. Copy the OFV.CAB file to your Desktop or to your Download location (if two or more OFV.CAB files are found in the results, copy any of them it’s the same file).
- Navigate to the location where you copied the OFV.CAB file and extract its contents.
- Double-click at extracted OFV.msi file to install the Microsoft Office File Validation Add-in for Office 2007 manually.
- Ask Yes at 'User Account Control' window.
- When the installation is completed, go to Windows Update and click Retry.
- That's it! This time Windows will check and install all available updates without displaying the error 0x80240023.
- If everything is OK, delete the OFV.CAB and the OFV.MSI files from where you copied them
(e.g. your Desktop), and continue your job.
Greetings form Bs.As.
Sylvia