When running an attachement Storarge Migration there may be failed files on completion (4277817)

When running an attachment storage migration from the administration website, on completion it may show failed files:

The migration is performed by the dataloader service and as such the dl.wlog files can be inspected to find the cause of the failed files. For example the follow error shows that the file is missing:

ERROR SL2.Migration.FileManagement - {{614900dc-ce7c-43b5-91a0-e92706ce4b9d}} Read attachment which AttachmentFileID = 862675 from original storage location is failed: The External storage key = '862675|862675.exe' does not exists.

To find the location of the logs folder, open the Archive Manager Configuration Console and select General Settings. There may be 11 files named dl.wlog to dl.10.wlog that need to be searched for errors.