When refreshing in the browser you may come across this error: "External Data Refresh Failed An error occurred while working on the Data Model in the workbook. Please try again. We were unable to refresh one or more data connections in this workbook. The following connections failed to refresh: <Connection>...

We have been seeing Excel Services/PowerPivot data refresh issues using SharePoint 2013 and Office Web Apps (OWA). Some customers have been running into issues when attempting to refresh data in a PowerPivot workbook on SharePoint 2013 using OWA server, and are seeing errors similar to the following...