I am getting this error when trying to merge TFS2008. There are no pending changes on either source or destination branches.
TF14083: The item {0} has a pending merge from the current merge operation, please resolve and check in the current merge and merge again to pick up this change.
Did you read this article?
One of the suggestions there is to try the operation in a new workspace.
Also, if you have renamed or deleted one or more branches/folders, there might be changes in your workspace you’re not aware of. Is there anything (even outside the source and target) in your Pending Changes window?