Import from an exsiting gitlab with url failed

Hi, i had an old version gitlab instance 10.3.5, and a new version gitlab instance 12.1.3. When i import project from old to new by using url, it always failed, and the application.log shows message like August 08, 2019 13:57: The Lfs import process failed. 5:GetRepoPath: not a git repository '/data/gitlab/git-data/repositories/base/service.git' . When i check the repositories folder, i found that there is only, the service.git is missing.
Thanks for any help!