This article describes some side effects that occur after you apply the April 2021 security updates for Microsoft Office, and provides help to eliminate the side effects.
Notifications during file load
Some Office files, templates, and add-ins can be manipulated to harm your computer. After you install the April 2021 security updates for Office, your computer might display a notification and disable some of these files, even if the files were originally obtained from Microsoft. For more information about this issue and how to re-enable the disabled content, see KB5001196.
Add-in languages in Office 2010
If you have multiple languages of Office 2010 installed, some add-ins, such as the Analysis ToolPak or Solver, might no longer appear in your desired language after you install KB 2553491 and KB 3017810.
To revert the language that's used by these add-ins to your desired language, uninstall the desired language version of the KB 2553491 and KB 3017810 updates, and then reinstall KB 2553491 and KB 3017810. To do this, follow these steps.
Note: For more information about how to uninstall an Office update if you are using Windows 10, see Remove an installed Windows update. If you are using an earlier Windows operating system, see Uninstall Office updates.
Open Installed Updates in Control Panel.
Locate and select the corresponding update for KB 2553491 according to your desired language. If your desired language is English, use the KB 2553491 update under the "Microsoft Office Excel 2010" section. If your desired language is not English, look in the corresponding language section. For example, for Swedish, use the the KB 2553491 update under the "Microsoft Office Excel MUI (Swedish) 2010" section.
Select Uninstall, and complete the successive operations.
Note: Restart the computer if you're prompted to do this.
Repeat steps 2 and 3 for KB 3017810.
Re-install KB 2553491 and KB 3017810. To make sure that the updates are reinstalled, see Install Office updates.
If these steps fail, you may have to repair Office and try these steps a second time. For instructions, see Repair an Office application.
Add-in languages in Office 2013
As of KB3178639 and KB4504735 for Office 2013, the language that the Analysis ToolPak and Solver add-ins in Excel use will follow the Office display language setting instead of relying upon the order in which languages are installed. For more information about the previous behavior, see Excel add ins do not follow Office user interface language setting. To set the new desired display language, see Change the language Office uses in its menus and proofing tools.
Note: KB4504735 must be installed in order for the Analysis ToolPak add-in to follow the Office display language setting.