Can not `git stash push -- .`

I tried to stash staged files with the command above, but got an error. I even change directory to the top level (where .git is located) and try to provide pathspec. Same result :( ``` $ git stash push -S -m "core -> ubuntu Migration" -- tools/ec2.tf tools/init.conf Saved working directory and index state On branch/xxx: core -> ubuntu Migration error: patch failed: state.d/terraform.tfstate.backup:2 error: state.d/terraform.tfstate.backup: patch does not apply Cannot remove worktree changes ```

Is there a way to stash only selected staged files from current subdirectory, eg. `git diff --staged .`

Thank you.