TF262600: This SharePoint site was created using a site definition that requires data from Team Foundation Server. However, the site is not currently associated with data for a team project

Errors:

TF262600: This SharePoint site was created using a site definition that requires data from Team Foundation Server. However, the site is not currently associated with data for a team project. To ensure that this site functions correctly, you must configure a team project to refer data for that project to this site. For more information, see this topic on the Microsoft Web site: How to: Add a Team Project Portal.

This site doesn't have a default Team Project. You can explicitly select a specific Team Project.
This web part is not configured properly. Click here to configure web part in tool pane.

Explanation

This issue was caused by missing permissions for the [TEAM FOUNDATION]\SharePoint Web Application Services group to the team project. I get into the issue whenever I detach and attach the same collection (side by side) to different TFS App tiers for testing/R&D

Soultion

1) Add and grant READ permission for [TEAM FOUNDATION]\SharePoint Web Application Services group to the affected team projects.

2) use tfsredirect.aspx to refresh the cache

http://SharePointServer/sites/CollectionName/TeamProjectName/
_layouts/TfsRedirect.aspx?tf:type=webaccess&tf:test=1&tf:clearcache=1

Note : This page should not return any errors and the value for TeamFoundation.Temp.LastRefreshDate should include the current date.

3) Repair the connections between TFS and SP

• Open the Team Foundation Server Administration Console
• Expand the Application Tier in question (the one hosting the Team Project Collection and Team Project with the problem)
• Highlight the SharePoint Web Applications node.
• In the SharePoint Web Applications list, highlight the appropriate connection and then click "Repair Connection"