Cannot edit an email attachment in OWA in an Exchange Server 2016 environment

Consider the following scenario:

• Cumulative Update 8 for Microsoft Exchange Server 2016 is installed in the Exchange Server environment.
• You receive an email message from a Microsoft Outlook 2016 client.
• The message contains an Office attachment, such as a Word doc, Excel workbook, or PowerPoint presentation.
• The signature in the message contains an image, such as a .gif or .png file.
• You open the message in Outlook Web App (OWA).

In this scenario, if you click Preview to view the attachment as soon as the email message opens, and then you click Edit and Reply, you cannot edit the attachment. Additionally, you receive the following error message:

This issue occurs because OWA incorrectly sends the image signature instead of the attachment to the back-end server.

Exchange Server 2016

To resolve this issue, install Cumulative Update 10 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.

Learn about the terminology that Microsoft uses to describe software updates.