Checking out Git tag leads to detached HEAD state

Question

I m developing a deployment script for my git project and I just started using tags  I ve added a new tag called v2 0   git tag -a v2 0 -m  Launching version 2 0    And I ve pushed this tag to the remote repository  git push --tags   When I try to execute the deployment script and check out the v2 0 tag I get this message      You are in  detached HEAD  state  You can look around  make experimental changes and commit them  and you can discard any commits   you make in this state without impacting any branches by performing   another checkout  If you want to create a new branch to retain commits   you create  you may do so  now or later  by using -b with the checkout   command again  Example    git checkout -b new branch name HEAD is now   at   Is that normal  The repository is in limbo because if I do   git branch   I get this output      no branch    master   Sorry if this is obvious but I couldn t figure it out

User · Accepted Answer

Okay  first a few terms slightly oversimplified    In git  a tag  like many other things  is what s called a treeish  It s a way of referring to a point in in the history of the project  Treeishes can be a tag  a commit  a date specifier  an ordinal specifier or many other things    Now a branch is just like a tag but is movable  When you are  on  a branch and make a commit  the branch is moved to the new commit you made indicating it s current position    Your HEAD is pointer to a branch which is considered  current   Usually when you clone a repository  HEAD will point to master which in turn will point to a commit  When you then do something like git checkout experimental  you switch the HEAD to point to the experimental branch which might point to a different commit    Now the explanation   When you do a git checkout v2 0  you are switching to a commit that is not pointed to by a branch  The HEAD is now  detached  and not pointing to a branch  If you decide to make a commit now  as you may   there s no branch pointer to update to track this commit  Switching back to another commit will make you lose this new commit you ve made  That s what the message is telling you    Usually  what you can do is to say git checkout -b v2 0-fixes v2 0  This will create a new branch pointer at the commit pointed to by the treeish v2 0  a tag in this case  and then shift your HEAD to point to that  Now  if you make commits  it will be possible to track them  using the v2 0-fixes branch  and you can work like you usually would  There s nothing  wrong  with what you ve done especially if you just want to take a look at the v2 0 code  If however  you want to make any alterations there which you want to track  you ll need a branch   You should spend some time understanding the whole DAG model of git  It s surprisingly simple and makes all the commands quite clear

User · Answer

Yes  it is normal  This is because you checkout a single commit  that doesnt have a head  Especially it is  sooner or later  not a head of any branch   But there is usually no problem with that state  You may create a new branch from the tag  if this makes you feel safer

[git] Checking out Git tag leads to "detached HEAD state"

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