git diff --cached: refname 'HEAD' is ambiguous

i use git diff --cached command then i got warning: refname 'HEAD' is ambiguous.

now if i used git branch i am getting Error like that

error: refs/description points nowhere!
error: refs/index points nowhere!
error: refs/packed-r开发者_StackOverflow中文版efs points nowhere!
error: refs/config points nowhere!
  205010_v2

Looks like the top-level files in your .git directory (or another .git directory) were somehow copied to .git/refs.

The ambiguous ref name warning is probably because there is both .git/HEAD and .git/refs/HEAD. If both files exist, the name HEAD could refer to either file, hence the warning. It's a warning and not an error because Git will always choose .git/HEAD over .git/refs/HEAD. See git help revisions for documentation on how Git resolves reference names.

The "points nowhere" errors are from non-reference files in the .git/refs directory.

To fix, delete the following files after backing them up:

• .git/refs/HEAD
• .git/refs/description
• .git/refs/index
• .git/refs/packed-refs
• .git/refs/config