I had this nagging problem on one instance where the Excel dashboards on a TFS 2010 instance would not bring up the data.
Here is how I fixed it (hopefully) someone else will benefit. There could be more than one reason for this error to manifest. In my case the following is what I did.
- Log into your SharePoint 2010 server with admin credentials
- Open SharePoint Central Administration
- Open Application Management
- Click Manage Service Applications (under Service Applications)
- Click Secure Store Service (not the proxy)
- Check on the SSS “Target Application ID”
- Then click on “Set Credentials”.
- Make sure the “Windows User Name” and “Windows Password” are the correct ones. Usually it appears blank. In my case I set it to the domain TFSService account and password.
- Restart the IIS Server and then go back to the Project portal and refresh OR launch the portal from the Team Project node in Team Explorer.
- This fixed it.