When trying to save changes to page layout in Experience Editor, errors appear and the page does not save.
The details in the logs showed:
System.Xml.XmlException Message[1]: Root element is missing.
I could see this was an issue to do with DyanamicPlaceholdersDebug.OnItemSaved failing but wasn't sure what.
After some debugging by overriding the pipeline with my own I figured out this was due to an empty _renderings field. The _finalrenderings field was populated but the _renderings field wasn't and the Dynamic Placeholders save pipeline expects it to be.
This was due to a miss-configuration on the standard values of the template for the page. Updating this so that the standard values set a layout and components on the shared layout instead of the final layout solved the problem.
