Hi, Not quite sure where to submit bug reports about Git, this was the best I could find, so if there's a better place to do this, please let me know and I will. The short of this issue is that on Mac and Windows, if a branch has a slash in its name, changing it from lowercase to uppercase requires diving into .git/refs/heads/ and manually moving stuff around - I think the behavior should be at least something like this: http://stackoverflow.com/questions/26810252/how-to-change-my-local-github-branch-name-to-uppercase. It happens that on both Windows box, to rename a branch from "branch/name" to "BRANCH/NAME", one has to actually dive into .git/refs/heads/ because of how Windows handles upper/lowercase in directory paths. (Win7, mingw64 via Git for Bash, git version 2.7.0.windows.1) user@windows-box MINGW64 ~ $ mkdir sandbox && cd sandbox && git init Initialized empty Git repository in C:/Users/user/sandbox/.git/ user@windows-box MINGW64 ~/sandbox (master) $ touch empty.txt && git add empty.txt && git commit -m 'initialize repo' [master (root-commit) 761113d] initialize repo 1 file changed, 0 insertions(+), 0 deletions(-) create mode 100644 empty.txt user@windows-box MINGW64 ~/sandbox (master) $ git branch * master user@windows-box MINGW64 ~/sandbox (master) $ git checkout -b branch/name Switched to a new branch 'branch/name' user@windows-box MINGW64 ~/sandbox (branch/name) $ git branch * branch/name master user@windows-box MINGW64 ~/sandbox (branch/name) $ git branch -m BRANCH/NAME fatal: A branch named 'BRANCH/NAME' already exists. user@windows-box MINGW64 ~/sandbox (branch/name) $ git branch -m tmp user@windows-box MINGW64 ~/sandbox (tmp) $ git branch -m BRANCH/NAME user@windows-box MINGW64 ~/sandbox (BRANCH/NAME) $ git branch branch/NAME master user@windows-box MINGW64 ~/sandbox (BRANCH/NAME) $ mv .git/refs/heads/branch/ .git/refs/heads/BRANCH/ user@windows-box MINGW64 ~/sandbox (BRANCH/NAME) $ git branch * BRANCH/NAME master Interestingly, from inside an Ubuntu VM (with the directory in question mounted as a VBox fileshare), this is not an issue. A colleague on a Mac also reproduces the issue successfully (OSX 10.11.5, git 2.8.3): mac-box:sandbox user$ touch empty.txt && git add empty.txt && git commit -m 'initial commit' [master (root-commit) 1f4f1fa] initial commit 1 file changed, 0 insertions(+), 0 deletions(-) create mode 100644 empty.txt mac-box:sandbox user$ git branch * master mac-box:sandbox user$ git checkout -b branch/name Switched to a new branch 'branch/name' mac-box:sandbox user$ git branch -m BRANCH/NAME fatal: A branch named 'BRANCH/NAME' already exists. mac-box:sandbox user$ git branch * branch/name master mac-box:sandbox user$ git branch -m tmp mac-box:sandbox user$ git branch master * tmp mac-box:sandbox user$ git branch -m BRANCH/NAME mac-box:sandbox user$ git branch branch/NAME master mac-box:sandbox user$ mv .git/refs/heads/branch/ .git/refs/heads/BRANCH/ mac-box:sandbox user$ git branch * BRANCH/NAME master Thanks, Sam -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html