“External Data Refresh Failed An error occurred during an attempt to establish a connection to the external data source. The following connections failed to refresh:” error in SharePoint 2013 PowerPivot data refresh

Excel web app runs in SharePoint View ode and Office web server view mode. In URL, if see “xlviewer.aspx” it is running on SharePoint Mode. If URL Contains “WopiFrame.aspx”, excel web app is running in “Office Web Apps Server view Mode”. If we use OWA Server view mode, to view the workbooks, Some BI features like Excel Web Access Web part, Refresh ODataConnections web part, View and interact PowerPivot view/data models...

We have to apply suppression setting on the farm to work with slicers and refresh data. So that we can edit the document in browser with Office Web Apps. We can suppress the Office webapps using following PowerShell command,

New-SPWOPISuppressionSetting –Extension “XLSX” -Action “view” 

Reference articles:

http://blogs.msdn.com/b/analysisservices/archive/2012/12/21/refreshing-powerpivot-data-in-sharepoint-2013.aspx

http://blogs.technet.com/b/excel_services__powerpivot_for_sharepoint_support_blog/archive/2013/02/01/powerpivot-2013-refreshing-in-the-browser.aspx

http://blogs.technet.com/b/excel_services__powerpivot_for_sharepoint_support_blog/archive/2013/01/31/powerpivot-for-sharepoint-browser-refresh-fails-data-refresh-not-supported-in-office-web-apps.aspx

Unable to Refresh the Excel Connection in Excel Webaccess Webpart

If you are using an excel workbook with pivot in it, along with the Excess Webpart to display it. As you click on the Refresh all data connection.

It throws an error. The data connection uses windows authentication and user credentials could not be delegated. The following connection failed to refresh

Here is the resolution for this problem:

http://sharepointknowledgebase.blogspot.com/2012/05/data-refresh-failed.html