Most Valuable Professional

View Jan Karel Pieterse's profile on LinkedIn subscribe to rss feed
Subscribe in a reader

Subscribe to our mailing list

* indicates required

Audit !!!

Check out our RefTreeAnalyser
the ultimate Excel formula auditing tool.


Excel VBA Masterclass (English)
Excel VBA for Financials (Dutch)

Third party tools

Speed up your file

The best tool to optimise your Excel model!

Repair your file

Stellar Phoenix Excel Repair
Best tool to repair corrupt Excel sheets and objects
Home > English site > Articles > Add-ins do not load

Excel add-ins fail to load


Lately (I wrote this page on August 17, 2016) I've been getting reports from people complaining that they can no longer use add-ins. In this article I describe the problem and a solution.

The problem

Even though an add-in has been "installed" into Excel using the Add-ins dialog its userinterface does not show. This is that dialog:

Add-ins dialog of Excel

As you can see, some add-ins are checked. But sometimes the user-interface of an add-in fails to display. In fact, the add-in file will not open in Excel at all, even if you try from Windows Explorer, or from File, Open from within Excel. Without any error message.

The cause

A recent Office Security update has caused any file downloaded from the internet (so this includes add-ins) to be marked as Blocked. Even if those files were in a zip container, they are marked as blocked. And Excel will simply not open them.


Unblock the files! Like so:

1. Copy the file from the zip file to any folder

2. Right-click the file and choose properties:

Select file properties

3. Click the Unblock button:

Click Unblock

Other resources

If you have a folder full of blocked files, this page describes a way to unblock all of them using Powershell.

And a great article by fellow-MVP Jon Acampora: Excel Add-in Ribbon Disappears After Installation.

This article describes the mechanics of the problem very well:


Showing last 8 comments of 28 in total (Show All Comments):


Comment by: Ronald LaRiviere (29-5-2018 14:55:25)

I selected the options in options and when I open Excel, I get a Custom UI Error dialog box that reads as follows:

The custom UI associated with this document has been disabled by policy.


Comment by: Jan Karel Pieterse (29-5-2018 15:19:28)

Hi Ron,

Which is tech-speak which means your IT dept has decided for you that you do not want external tools to work properly. Unfortunately there isn't anything I can do about that :-(


Comment by: PhilUK (22-6-2018 10:44:37)

Hi Jan
Like many of your followers I have used your addin since Excel 2003 and have appreciated your work for many years
I am now using Excel 2016
When I try to add a new name I get an error message headed "API Clipboard Copy", which states "Memory location could not be Unlocked. Clipboard copy aborted"
The added name is then listed but typically shows as referring to the active cell only
I have tried to edit the "refers to" but the same error message appears
Can you offer any advice?


Comment by: Ricardo Hernandez Tablas (19-7-2018 18:30:32)

Excellent article, helped me a lot with some problems I was having with add-ins.

Thanks a lot


Comment by: Aslam (18-10-2018 08:19:12)

I was also having problem with Add-Ins and search alot of articles in this regard but didn't get any solution about, but this article helped me by Right Clicking property of add-ins and Unblocked the addins. now its working FINE many many thanks to the team.


Comment by: joan jiang (2-11-2018 20:38:01)

how many ways to insert the date picker function?


Comment by: Jan Karel Pieterse (4-3-2019 15:28:57)

test of new site


Comment by: Jan Karel Pieterse (4-3-2019 15:30:25)

test new site 2


Have a question, comment or suggestion? Then please use this form.

If your question is not directly related to this web page, but rather a more general "How do I do this" Excel question, then I advise you to ask your question here:

Please enter your name (required):

Your e-mail address (optional, will only be used to inform you when your comment is published or to respond to your question directly):

Your request or comment (max 2000 characters):

To post VBA code in your comment, use [VB] tags, like this: [VB]Code goes here[/VB].

I give permission to process this data and display my name and my comment on this website accoring to our Privacy Policy.