eXo Platform 3.5 has many changes on the data model and APIs. Therefore, if there are any new customized components in your eXo Platform extension that use eXo Platform 3.0 APIs, you need to check if they can work well in eXo Platform 3.5 or not. For more details, see the eXo Platform 3.5 APIs section.

Finally, you need to update your customized components if needed.