Knowledge base KB0237

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Conflict with Microsoft Azure Information Protection add-in: Subclassing error in PowerPoint and Excel

Problem

When I close PowerPoint or Excel, I receive the following error message:
CRITICALWITHMSG library\ui\win\safesubclassimpl.cpp(392): APIERR 1400 Invalid window handle.

When multiple PowerPoint (or Excel) files are open and the Microsoft Azure Information Protection (AIP) bar is shown below the ribbon, this error may occur when closing the last PowerPoint (or Excel) file. However, other add-ins must be present as well. The issue is reliably reproducible, e.g. when Capital IQ is enabled. For detailed reproduction steps, please click on: Read more

Reproduction with think-cell, Microsoft AIP and Capital IQ:

  1. Open new blank PowerPoint [or Excel] file
  2. Open second new blank PowerPoint [or Excel] file, e.g., with CTRL+N
  3. Make sure the Microsoft AIP bar is shown below the ribbon: Home > Sensitivity> tick Show Bar
  4. Go to S&P Capital IQ tab
  5. Charting > Charting > Launch Chart Builder
  6. Close 2nd file > Don't Save
  7. Close 1st file > Don't Save
    > CRITICALWITHMSG library\ui\win\safesubclassimpl.cpp(390): APIERR 1400 Invalid window handle.

Explanation

Such errors in think-cell are caused by a programming error in another add-in. Our developers analyzed the issue in detail. In this case the issue is caused by the Microsoft Azure Information Protection (AIP) add-in. According to our analysis, hooking/unhooking issues cause this problem when multiple add-ins are available. Read more

A hook is a mechanism by which a function can intercept events before they reach an application. The function can act on events and, in some cases, modify or discard them. For further details, please see KB0201.

Other add-ins known to cause such issues are listed in KB0169.

Solution

We received the feedback from Microsoft that the AIP client is in maintenance mode. Microsoft does not recommend using the AIP add-in for Office, because, i.e., "Add-ins are less stable because they can conflict with other add-ins that can result in Office apps hanging, crashing, or automatically disabling the add-in." Instead, Microsoft recommends using the Microsoft Information Protection (MIP) built-in labeling for Office apps.

Workaround

The problem seems to disappear when turning off the Microsoft AIP bar below the ribbon in PowerPoint and Excel. To turn it off, go to Home > Sensitivity > untick Show bar. In any case, please ask your internal IT for advice.

Contact support

In case you are still experiencing issues without the Microsoft AIP add-in, proceed as follows:

Please send us the think-cell log files. To do so, on the PowerPoint or Excel ribbon, select Insert > think-cell > Tools Tools Menu icon > Request Support. A new email will open with the log files automatically attached.

If Request Support works neither in PowerPoint nor in Excel, do the following: Read more

  1. Open a new File Explorer window.

  2. In the address field, enter %LOCALAPPDATA%\think-cell. Select Enter.

    Alternatively, you can open the think-cell folder by browsing the directory: Read more

    The full default filepath is C:\Users\USERNAME\AppData\Local\think-cell. Replace USERNAME with your username.

    If you can't find this folder, it's probably hidden. To show hidden items, in File Explorer, select one of the following:

    • Windows 7: Organize > Folder and search options > View > Show hidden files and folders
    • Windows 8, Windows 8.1, and Windows 10: View > Show/hide > Hidden Items
    • Windows 11: View > Show > Hidden Items

  3. Send all the files in the think-cell folder that end in log to our support team. These files may include any of the following:

    • excel_log.log
    • powerpnt_log.log
    • ppttc_log.log
    • setup_think-cell_VERSION_log.log
    • tcasr_log.log
    • tcindex_log.log
    • tcmail_log.log
    • tcrunxl_log.log
    • tcupdate_log.log

      • Additionally, if think-cell is active, please send us a screenshot of the About think-cell dialog. To open the About think-cell dialog, on the PowerPoint or Excel ribbon, select Insert > think-cell > Tools Tools Menu icon > About.