java.lang.AssertionError: Method must be called before the widget is rendered

“Method must be called before the widget is rendered.

 

AccordionLayoutContainer.onInsert(AccordionLayoutContainer.java:305)"

 

 there can be many reasons for this error, but the major one is an attempt to add to AccordionLayoutContainer a widget which is already rendered once.

It is helpful to "clone" the widget manually plus adding the new one to the AccordionLayoutContainer.