I recently started playing around with Visio Services in Sharepoint 2010. I set up data connections to SQL Server so I could display data for a few of the items in my drawing and everything was working fine in Visio, however when I viewed it in the SharePoint Web Part I started getting the following error:

“Visio Services was unable to refresh external data connections in this diagram because an underlying data source is unreachable. To resolve this issue, try again or ask your system administrator to make sure that all underlying data sources are available.”

One of the ways to get around this error and to get your data flowing freely again is to configure the Secure Store Service in Sharepoint 2010. You’ll need admin rights and access to SharePoint Central Administration to do so. Start off by navigating to the following page:

Central Administration—>Application Management—>Manage Service Applications—> Secure Store Service.

Select “New” from the edit ribbon and fill out the requested info, taking special note of what you put in “Target Application ID” as you’ll need that later. You’ll also need to select “Group” for the “Target Application Type”. Once complete you should have something similar to the screen below. Once finished click next.

You should now be prompted to enter what fields you want to provide values for. I used Windows Auth for my data connections, so I didn’t need to change anything on this screen (note this screen is not prompting you to type in the actual user name and password…only what info you’ll be providing later on) Once finished click next.

The third screen is pretty self-explanatory. I was setting this up in a demo virtual machine so I configured it as shown below. Once you’re done click OK.

Once you click ok you’ll be taken back to the screen we started on. You should now see a new item with the “Target Application ID” you entered in step one. Select the item by checking the select box on the left hand side, and then click “Set Credentials” up at the top (highlighted yellow in the picture below)

Now just enter in the credentials you want to use to access the data in your Visio drawing and then click OK.

Only one last thing to configure before we wrap this up. Navigate to Central Administration --> Application Management—> Manage Service Applications—> Visio Graphics Service.

Click on the “Global Settings” link and in the “Application ID” textbox type in the name you gave your “Target Application ID” in our first step and then click OK.

That should do it, no more nasty error messages, and your Visio drawing should be showing your data. As usual, feel free to send your questions or comments to the email on my contact page.