In version 4.51 of Email to Case Premium, Internet Creations introduced functionality for the Answer Customer action that allowed the component to resize based on the content. Unfortunately, this method is no longer supported within the Lightning Experience following the Spring 19 release of Salesforce.

To avoid this error with the Answer Customer action, upgrade to version 5.34 or later of Email to Case Premium through the AppExchange. The Answer Customer action can no longer automatically resize its height within the Lightning Experience, and will load with a default height of 650 pixels.

The following instructions allow you to create a custom action to load the Answer Custom action with a height different than the default.

1. Navigate to Setup | Object Manager | Case
2. Select "Button, Links, and Actions" and click "New Action".
3. Create your action matching the following parameters, and click Save.

• To avoid this error on each load of the Answer Customer action, Internet Creations advises upgrading to version 5.34 of Email to Case Premium off of the AppExchange.
• Users of Salesforce Classic are unaffected by this change.