# Git client bug with branch containing "." 3 messages from 2025-04-01 to 2025-04-01. Participants: Milan AJDINOVIC, Johannes Schindelin, brian m. carlson. Thread: https://gitlist.dev/t/63232 ## Milan AJDINOVIC, 2025-04-01 12:19 Subject: Git client bug with branch containing "." Message-ID: URL: https://gitlist.dev/e/VI1PR04MB695864E125F3381932332BDC91AC2%40VI1PR04MB6958.eurprd04.prod.outlook.com ``` What did you do before the bug happened? (Steps to reproduce your issue) On GitHub Enterprise server I have created a branch named: features/team1/feature./1.0/main in my repo. I tried to fetch the branch and switch to it. What did you expect to happen? (Expected behavior) I expected for branch to be switched to:features/team1/feature./1.0/main What happened instead? (Actual behavior) I got an error: fatal: cannot lock ref 'refs/heads/features/team1/feature./1.0/main': unable to create directory for .git/refs/heads/features/team1/feature./1.0/main What's different between what you expected and what actually happened? The branch did no switch. Anything else you want to add: From my analisys the problem is because my branch have "feature." in it and Windows can not create directory with "." at the end. Please review the rest of the bug report below. You can delete any lines you don't wish to share. [System Info] git version: git version 2.42.0.windows.2 cpu: x86_64 built from commit: 2f819d1670fff9a1818f63b6722e9959405378e3 sizeof-long: 4 sizeof-size_t: 8 shell-path: /bin/sh feature: fsmonitor--daemon uname: Windows 10.0 19045 compiler info: gnuc: 13.2 libc info: no libc information available $SHELL (typically, interactive shell): General ``` ## Johannes Schindelin, 2025-04-01 15:55 Subject: Re: Git client bug with branch containing "." Message-ID: <4dad78d0-efe2-e01f-cd5f-097259bf961f@gmx.de> URL: https://gitlist.dev/e/4dad78d0-efe2-e01f-cd5f-097259bf961f%40gmx.de In-Reply-To: ``` Hi Milan, On Tue, 1 Apr 2025, Milan AJDINOVIC wrote: > What did you do before the bug happened? (Steps to reproduce your issue) > On GitHub Enterprise server I have created a branch named: features/team1/feature./1.0/main in my repo. > I tried to fetch the branch and switch to it. > > What did you expect to happen? (Expected behavior) > I expected for branch to be switched to:features/team1/feature./1.0/main > What happened instead? (Actual behavior) > I got an error: fatal: cannot lock ref 'refs/heads/features/team1/feature./1.0/main': unable to create directory for .git/refs/heads/features/team1/feature./1.0/main > What's different between what you expected and what actually happened? > The branch did no switch. > Anything else you want to add: > From my analisys the problem is because my branch have "feature." in it and Windows can not create directory with "." at the end. That analysis and conclusion is correct, as per https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file: Do not end a file or directory name with a space or a period. Although the underlying file system may support such names, the Windows shell and user interface does not. The problem here is the directory name `feature.`. You cannot even track this locally, at least not with the way Git implemented its default refs backend because it wants to map the ref name to a path in the filesystem. Note: It _might_ pretend to work when you clone, but any subsequent fetch that updates that ref will fail. Your only chance to track the ref locally is to map it to a different name in your Git config, like so (`git config edit`): [remote "origin"] url = [...] fetch = +refs/heads/*:refs/remotes/origin/* fetch = ^refs/heads/features/team1/feature./1.0/main fetch = refs/heads/features/team1/feature./1.0/main:refs/heads/features/team1/feature/1.0/main After that, you should be able to fetch and then check out that branch under the name on the right-hand side, i.e. without that `.` after `feature`. Ciao, Johannes > Please review the rest of the bug report below. > You can delete any lines you don't wish to share. > > > [System Info] > git version: > git version 2.42.0.windows.2 > cpu: x86_64 > built from commit: 2f819d1670fff9a1818f63b6722e9959405378e3 > sizeof-long: 4 > sizeof-size_t: 8 > shell-path: /bin/sh > feature: fsmonitor--daemon > uname: Windows 10.0 19045 > compiler info: gnuc: 13.2 > libc info: no libc information available > $SHELL (typically, interactive shell): > > > > > > > > > > General > > > ``` ## brian m. carlson, 2025-04-01 21:16 Subject: Re: Git client bug with branch containing "." Message-ID: URL: https://gitlist.dev/e/Z-xXsCs3Wr6NwYx1%40tapette.crustytoothpaste.net In-Reply-To: ``` On 2025-04-01 at 12:19:47, Milan AJDINOVIC wrote: > What did you do before the bug happened? (Steps to reproduce your issue) > On GitHub Enterprise server I have created a branch named: features/team1/feature./1.0/main in my repo. > I tried to fetch the branch and switch to it. > > What did you expect to happen? (Expected behavior) > I expected for branch to be switched to:features/team1/feature./1.0/main > What happened instead? (Actual behavior) > I got an error: fatal: cannot lock ref 'refs/heads/features/team1/feature./1.0/main': unable to create directory for .git/refs/heads/features/team1/feature./1.0/main > What's different between what you expected and what actually happened? > The branch did no switch. > Anything else you want to add: > From my analisys the problem is because my branch have "feature." in it and Windows can not create directory with "." at the end. I think that's correct as to why it's not working. Git by default uses the files ref backend, which stores the data in files in the repository, and in your case, Windows is unable to create that directory. That's unfortunately a limitation of Windows and we can't do anything about it. We allow those branches because Unix systems don't have this problem and users working with Unix-only repositories might want to use them. > git version 2.42.0.windows.2 If you use the latest release (2.49.0), you can probably switch to the experimental reftable backend using `git refs migrate --ref-format=reftable`, which will not have this problem. However, please make a backup of your repository first, since we've seen some bugs during the conversion that have caused problems, including with stashes. -- brian m. carlson (they/them) Toronto, Ontario, CA ```