Excel SSAS Tabular error: An error occurred during an attempt to establish a connection to the external data source

Question

Hello there,
I have an Excel report I created which works perfectly fine on my dev environment, but fails on my test environment when I try to do a data refresh.
The key difference between both dev and test environments is that in dev, everything is installed in one server:
SharePoint 2013
SQL 2012: Database Instance, SSAS Instance, SSRS for SharePoint, SSAS POWERPIVOT instance (Powerpivot for SharePoint).
In my test and production environments, the architecture is different:
SQL DB Servers in High Availability (irrelevant for this report since it is connecting to the tabular model, just FYI)
SQL SSAS Tabular server (contains a tabular model that processes data from the SQL DBs).
2x SharePoint Application Servers (we installed both SSRS and PowerPivot for SharePoint on these servers)
2x SharePoint FrontEnd Servers (contain the SSRS and PowerPivot add-ins).
Now in dev, test and production, I can run PowerPivot reports that have been created in SharePoint without any issues. Those reports can access the SSAS Tabular model without any issues, and perform data refresh and OLAP functions (slicing, dicing, etc).
The problem is with Excel reports (i.e. .xlsx files) uploaded to SharePoint. While I can open them, I am having a hard time performing a data refresh. The error I get is:
"An error occurred during an attempt to establish a connection to the external data source [...]"
I ran SQL Profiler on my SSAS Server where the Tabular instance is and I noticed that every time I try to perform a data refresh, I get the following entries:
Every time I try to perform a data refresh, two entries under the user name ANONYMOUS LOGON.
Since things work without any issues on my single-server dev environment, I tried running SQL Server Profiler there as well to see what I get.
As you can see from the above, in the dev environment the query runs without any issues and the user name logged is in fact my username from the dev environment domain. I also have a separated user for the test domain, and another for the production domain.
Now upon some preliminary investigation I believe this has something to do with the data connection settings in Excel and the usage (or no usage) of secure store. This is what I can vouch for so far:
Library containing reports is configured as trusted in SharePoint Central Admin.
Library containing data connections is configured as trusted in SharePoint Central Admin.
The Data Provider referenced in the Excel report (MSOLAP.5) is configured as trusted in SharePoint Central Admin.
In the Excel report, the Excel Services authentication settings is set as "use authenticated user's account". This wortks fine in the DEV environment.
Concerning SecureStore, PowerPivot Configurator has configured it the PowerPivotUnnattendedAccount application ID in all the environments. There is
NO configuration of an Application ID for Excel Services in any of the environments (Dev, test or production). Altough I reckon this is where the solution lies, I am not 100% sure as to why it fails in test and prod. But as I read what I am
writing, I reckon this is because of the authentication "hops" through servers. Am I right in my assumption?
Could someone please advise what am I doing wrong in this case? If it is the fact that I am missing an Secure Store entry for Excel Services, I am wondering if someone could advise me on how to set ip up? My confusion is around the "Target Application
Type" setting.
Thank you for your time.
Regards,
P.

Answer 1

Hi Rameshwar,
PowerPivot workbooks contain embedded data connections. To support workbook interaction through slicers and filters, Excel Services must be configured to allow external data access through embedded connection information. External data access is required
for retrieving PowerPivot data that is loaded on PowerPivot servers in the farm. Please refer to the steps below to solve this issue:
In Central Administration, in Application Management, click Manage service applications.
Click Excel Services Application.
Click Trusted File Location.
Click http:// or the location you want to configure.
In External Data, in Allow External Data, click Trusted data connection libraries and embedded.
Click OK.
For more information, please see:
Create a trusted location for PowerPivot sites in Central Administration:
http://msdn.microsoft.com/en-us/library/ee637428.aspx
Another reason is Excel Services returns this error when you query PowerPivot data in an Excel workbook that is published to SharePoint, and the SharePoint environment does not have a PowerPivot for SharePoint server, or the SQL Server Analysis
Services (PowerPivot) service is stopped. Please check this document:
http://technet.microsoft.com/en-us/library/ff487858(v=sql.110).aspx
Finally, here is a good article regarding how to troubleshoot PowerPivot data refresh for your reference. Please see:
Troubleshooting PowerPivot Data Refresh:
http://social.technet.microsoft.com/wiki/contents/articles/3870.troubleshooting-powerpivot-data-refresh.aspx
Hope this helps.
Elvis Long
TechNet Community Support