fatal: Cannot update paths and switch to branch 'gitlab' at the same time.

I believe this occurs when you are trying to checkout a remote branch that your local git repo is not aware of yet. Try:

git remote show origin

If the remote branch you want to checkout is under “New remote branches” and not “Tracked remote branches” then you need to fetch them first:

git remote update

git fetch

Now it should work:

git checkout -b local-name origin/remote-name

还有一种方法：

直接执行如下命令：

git fetch --all && git fetch -t