How to solve: Please specify which branch you want to rebase against

If you add a remote to an existing repository or you create a new branch,
you have to set up the remote branch tracking yourself.

This could be an error output, after running a git pull --rebase or you try to push with git push:

There is no tracking information for the current branch.
Please specify which branch you want to rebase against.
See git-pull(1) for details.

    git pull <remote> <branch>

If you wish to set tracking information for this branch you can do so with:

    git branch --set-upstream-to=origin/<branch> local_branch_name

see local and remote branches

run git fetch --all to update the references to remote branches.

then git branch --all to see all local and remote branches.

e.g.:

~/D/p/christian-fei.github.io (master ↩) git branch --all
  css-grids
  dev
* master
  remotes/origin/HEAD -> origin/master
  remotes/origin/dev
  remotes/origin/master

setting up remote branch tracking

Let’s suppose the new branch is dev.

In this case, you would run:

git branch --set-upstream-to=origin/dev dev