This content cannot be displayed in a frame

Problem Statement: I was trying to navigate different pages in SharePoint Hosted app. When i click on some page in the App UI, i am getting this error.
Root Cause: All pages should have allow framing tag.
Solution:
Add below tag in side asp:Content.

<WebPartPages:AllowFraming ID="AllowFraming1" runat="server" />

This content cannot be displayed in a iframe

sharepoint page viewer this content cannot be displayed in a frame
Error: "This content cannot be displayed in a frame"
Solution:
Open the .aspx page where you are adding iframe using SharePoint designer.
Add below tag in the source page.
<WebPartPages:AllowFraming runat="server" />

Source page mean: The page which you are using in iFrame.
Not the page where iFrame is added.