Is the latest version of Excel 365 blocking HtmlHelp??

James Huntington 1 Reputation point

We use compiled html help (.CHM files) and the HtmlHelp API to provide help for users of our Microsoft Excel add-in. But this this week we've suddenly had a few customers complain that the help doesn't open. They click the link and nothing happens.

Testing this, I can see calls to the HtmlHelp function now return a HWND of NULL. This still works fine in older versions of Excel that we support, the help appears and we can the HWND of the help window. So, because it works in older versions I can only assume this is a change in Office 365, rather than a Windows 10 change. The CHM files themselves can still be opened using Windows File Explorer and the same API calls in a standalone application works fine.

Are any other add-ins developers having this problem? Is this to prevent security flaws in the browser used by HtmlHelp? I would move to standard html help and display it in a browser, but we have a few interactive tutorials that send messages back to our application to demonstrate certain steps. That wouldn't be possible with browser based help. Anyone else having this issue? Is this an official change from Microsoft?

Office Development
Office Development
Office: A suite of Microsoft productivity software that supports common business tasks, including word processing, email, presentations, and data management and analysis.Development: The process of researching, productizing, and refining new or existing technologies.
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  1. julia555 6 Reputation points

    Context help via HtmlHelp( ) has suddenly started working on at least few computers in our company!

    Quiet Windows/Office update??

    Does anyone know any details?

    Anyway, many thanks to Microsoft!

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  2. julia555 6 Reputation points

    Yes, we have the same problem!

    We have been using HtmlHelp function to call Help file for a long time and have never had any problems.
    Suddenly, as you mentioned, HtmlHelp function returns a HWND of NULL!

    Can anyone from Microsoft help?

    Thank you,

    No comments

  3. Kevin Carpenter 1 Reputation point

    We're having similar issues with ACCESS VBA. the hhctrl.ocx checks out as fine. NO IDEA what changed, but suddenly our context help fusing the helphtml api doesn't work.

  4. Kevin Carpenter 1 Reputation point

    rolling back office to a Feb 16 version fixed the issue for our Access app. using 365.
    from command prompt as administrator....."C:\Program Files\Common Files\Microsoft Shared\ClickToRun\OfficeC2RClient.exe" /update user updatetoversion=16.0.12730.20236 rolled it back - then be sure and turn off automatic updates. worked like a charm.