我正在尝试在旧存储库中推送新的跟踪文件。当我提交显示的错误时，如下所示：
E:\C and C++ Programs>git commit -m "Add new file"
fatal: Unable to create 'E:/C and C++ Programs/.git/index.lock': File exists.
Another git process seems to be running in this repository, e.g.
an editor opened by 'git commit'. Please make sure all processes
are terminated then try again. If it still fails, a git process
may have crashed in this repository earlier:
remove the file manually to continue.
为什么显示此错误以及如何解决？ 我正在使用Windows 10专业版。