I've been configuring a few different issue types, and all of a sudden I saw that my pie chart for the project displayed the following error when using the Statistic type: Components:
An internal server error occurred when requesting resource /rest/gadget/1.0/piechart/generate.
Clicking on the error hyperlink produced the following error:
{errorMessages: ,errors: {field:projectOrFilterId,error:gadget.common.required.query} }
My project has 3 issue types, and component is populated for all of them. I don't see why an error is being produced when all the data exists. When I choose other statistic types such as assignee, the data displays fine.