This affects Report predefined destinations and standard Lasernet Emailing:

Cause
Dynamics 365 Finance and Operations 10.0.25

Microsoft has introduced a new HTML editor control and no longer supports the Legacy HTML editor in version 10.0.25.
 
Updates to client feature states with version 10.0.25 - Dynamics 365 Release Plan | Microsoft Docs 

Lasernet Connector Parameters are set to Legacy HTML editor, which causes an error message to pop up when entering the destinations for emailing. This is due to Dynamics 365 FO 10.0.25. 

Solution

To stop this message from popping up,  follow these steps:

1. Navigate  to Modules > Lasernet > Setup > Parameters.

2. Select the Email tab and change the value to HTML editor in the Emailing body editor type field by clicking the dropdown menu.

The HTML editor has been introduced in the Lasernet Connector 6.16.

If you are using a Lasernet Connector version prior to 6.16 and do not use HTML for email body text, you can also switch to Plain text.

Version 10.0.22 of Finance and Operations Apps

When you are using the  HTML editor control and try to open the lookup for Styles, Format, Font, or Size, you will get an error dialog saying: "An unexpected client error has occurred". Once this happens, clicking the Save button on the dialog will not solve the issue.

Solution

Combo box selections in the toolbar would cause this client error due to having an incorrect context. The correct context is now in place.