Hi,
There's a bug in the calender widget. I had the same error as above mentioned. This error was there as long as I selected a Event title over an association. After I made an after commit flow to get all the info in one entity the error was gone.
Looks like the calender widget can't handle showing a title name over an association.
Regards, Marten
The same problem occured with me after setting up a new local environment. After a number of deployments it was solved, possibly because there is now some data in the database. I would suggest to: 1. add some displayable (for the calendar) data in your database, be sure to have also data in associations of the displayed object 2. clean the deployment directory; 3. deploy a couple of times. Answer maybe not satisfactory, but with me it works most of the times.
I just had this error on a calendar widget as well.
My solution: Making sure via XPath usage in the Data source tab, that Data for “Title” in EventData was not empty. No more error from this calender.