Push fails in GitKraken with errormessage "Push Failed cannot read property 'fullName' of undefined"

I had this problem as well when there was a HEAD tag at a commit behind the current local master or origin/master.

Try double-clicking your local master (which eliminates HEAD) and then push your changes.

Note that if you do not have a local master, right-click on remote origin master and choose 'Checkout origin/master'. Then pull, commit, push your changes.

Going to add my tuppence here. I had a casing mismatch on a folder between a local branch and the remote.

Make sure when you create a branch that the case matches remote i.e. if your remote folder is called Task, don't create a local branch called task\1234-my-task.

The fix by @notedible didn't work for me. But it led me to simply going to the command line and doing a git status

$ git status
On branch feature/RES-523
Your branch and 'origin/feature/RES-523' have diverged,
and have 13 and 2 different commits each, respectively.
  (use "git pull" to merge the remote branch into yours)
nothing to commit, working tree clean

$ git pull
From https://bitbucket.org/my-repo
 * [new branch]        feature/RES-523 -> origin/feature/RES-523
Auto packing the repository in background for optimum performance.
See "git help gc" for manual housekeeping.
Already up-to-date.

Boom! Good to go.