Sometimes when a migration runs there are issues with the origin source database that need to be manually reconciled. Common examples are duplicate items due to case sensitive paths in CVS, StarTeam, and SVN, migrating over to TFVC and occupying the same path due to TFVC not supporting case sensitive paths.
Settings like the "ItemExistsHandler" can attempt to automatically correct issues with adds and edits of duplicate items, but deletes and renames can cause problems that need to be addressed as in the following use case.
Add /A Add /a Rename /A to /B Rename /a to /b Delete /b
With this use case, the add of /a gets overlaid onto /A. The first rename of /A to /B succeeds, but then the rename of /a to /b will fail because only one version of A existed in TFVC and it was already renamed.
From looking at the history, /b will eventually be deleted so to correct the issue the actions to rename of /a to /b can be skipped to get past this issue as well as the delete of /b.
To skip these actions select the Tools -> Session Details menu item. When the Session Details dialog displays it should look like the following:
Then press the "Get Pending Change Group" button to navigate to the Change Group that is having the problem.
To correct the issue with the current Change Group, select the action that renames the target paths for the rename of /a to /b, and then press the "Skip Action" button to omit it from the migration. If you realize you selected the wrong action, selecting the same item again and then pressing "Restore Action" will include it in the migration again.
Then to remove the action for the delete of /b, the "Get Next Change Group" button can be used to move to the next change group, where the delete action can be skipped.