Engagement messenger portal is not opening.Issue Engagement messenger makes it easy to extend self-service across an organization's web properties. The issue is the engagement messenger portal is throwing the error "instance is unavailable". Steps to reproduce: Open https://<your-instance>.service-now.com/5401fb501b3ee010431ba606624bcbc2The instance unavailable error is thrown. Below console error is observed for the issue. @servicenow/ui-renderer-snabbdom For component <sn-component-openframe component-id="x1uwlshsd0en-79"/> with origin 'onStateChange': An Error occurred in <sn-component-openframe component-id="x1uwlshsd0en-79"/>. COMPONENT_ERROR_THROWN action type is dispatched with error details.TypeError: Cannot read properties of null (reading 'height')CauseChecked and found that the below response header name is incorrectly configured. https://<your-instance>.service-now.com/nav_to.do?uri=sys_response_header.do?sys_id=ceb9d86c1bfee010431ba606624bcbcdResolutionChange the response header name as below and save the record which resolves the issue. Value:Content-Security-Policy. Reference: Create HTTP response headers for Engagement Messenger.