I just upgraded to a new version and my pages are not displayed correctly
If you are using a custom theme (one which did NOT ship with the Exponent package), it may be using some obsolete features which are no longer included in the system.
Fix: the first step is to go to the Exponent, Developer Tools, Extensions menu to 'Manage Themes.' Preview (click on the magnifying glass) a standard 'shipped' theme such as 'Simple Theme.' If the site seems to 'work' correctly under the standard theme, it's likely that one of the theme customizations is the source of the issue.
You will have to consult the vendor of the custom theme for assistance in obtaining a version compatible with your installation. In many cases it is either the theme or subtheme template or the custom module views making 'calls' to obsolete methods no longer used in Exponent. You can find more information about creating and editing themes here under the 'Theme Variations' or 'Modules and Views' topics.