"This content cannot be displayed in a frame" appears when trying to access the Script Editor Web part via SharePoint online
kbt152628
PRODUCTIssue
When logging in with K2 Trust for Azure AD on SharePoint online via the Script Editor web part, the worklist will display "This content cannot be displayed in a frame" after logon.
Symptoms
The Script Editor web part will not be available for any users to action tasks.
Resolution
To correct this issue you will need to determine what Authentication is required.
Option 1
It is expected to see this error in the Script editor web part if you are not logged in with SharePoint Credentials, so you need to sign out properly from SharePoint Online.
Option 2
It is recommended that the K2 Smart Form Viewer web part be used as this is integrated with K2 Authentication.