Error when editing an equation in Office


When you try to edit an equation that was inserted using Equation Editor 3.0 in an Office application (such as Word), you see the following error:

Microsoft Equation is not available.

Screenshot of the error after editing an equation that is inserted using Equation Editor 3.0 in an Office application.


Equation Editor 3.0 was a third-party component built by Design Science ( that was included in many versions of Office, but due to security issues with its implementation has been removed. Office now includes a newer equation editor.

For more information about the security issue, see CVE-2017-11882 | Microsoft Office Memory Corruption Vulnerability.


While the new equation editor will not edit existing equations that were created by Equation Editor 3.0, it allows you to insert new equations, common equations, or ink equations written by hand. The equation function can be found in Word, Excel, or PowerPoint under the Insert tab.

For more information about inserting and editing equations, including a short video tutorial, see Write an equation or formula.

Alternatively, the third-party app MathType enables you to edit Equation Editor 3.0 equations without security issues. MathType is now part of the Wiris Suite. You can download a free MathType 30-day trial at: Welcome Microsoft Equation Editor 3.0 users

More information

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.