问题描述：

Git 提交（commit 或 discard, remove等）时，报错，显示错误如：

fatal: Unable to create 'XXXXXX/.git/index.lock': File exists.

If no other git process is currently running, this probably means a
git process crashed in this repository earlier. Make sure no other git
process is running and remove the file manually to continue.

解决办法：

找到index.lock 删除即可