Our project was running on AEM 6.0 where we created our existing pages. After upgrading to AEM 6.1, we installed the existing pages using package manager. All our components/templates/clientlibs got installed perfectly.
But when we try to open the new page and drag/drop new components from sidekick, first of all no components are showing in sidekick and when we try to add using design mode, page gives internal server error in console. Please suggest.
Do you have the custom parsys component inside your /apps project ? if yes, then you need to make some corrections in the parsys component code to see the components in the sidekick. There are some changes in Out of box parsys between AEM6.0 and AEM6.1. Can you please verify in geometrixx if same issues exists also there, if not, then you need to make some changes in your template and component code.
Also, you probably need to make some changes in the components dialog hierarchy to make it compatible working with AEM6.1. Sounds like, good amount of work