User report on git 2.55.0

User report on git 2.55.0

[Ramkumar Ramachandra]

Hi,

I recently bumped to the latest version of git on macOS via homebrew, and here's what I've noticed:

1. git-replay now updates the ref, simplifying my git-reply-checkout script. Someone on this list recommended it to me in response to an issue I had a long time ago, and I think I can safely say that git-replay is an invaluable tool. Thanks!
2. git-pull often fails with a dangling remote ref error, and fails to update the current branch (main, in my case): the workaround is to reset-hard to origin/main. I'm not sure if this is a GitHub issue, or a bug in core git: I've never encountered this behavior on older versions of git, with the exception of submodules.
3. git-diff sometimes exits with 0 code without printing a diff, even though the worktree is dirty: the workaround is to run it again. I've never encountered this behavior on older versions of git, and I think it might be a subtle race in core git.
4. `git checkout -` sometimes fails with an invalid ref error after a pull, where the previous branch is a local branch. I don't know if this is due to a background git-gc with some behavior change, but I never encountered this behavior on older versions without an operation that would cause this.

Before digging further to find the root cause, I'd like to know if there is some explanation I'm missing, or if these are known issues?

Thanks.

Warm regards,
Ram

Re: User report on git 2.55.0

[brian m. carlson]

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On 2026-09-04 at 18:05:43, Ramkumar Ramachandra wrote:
> Hi,
> 
> I recently bumped to the latest version of git on macOS via homebrew, and here's what I've noticed:
> 
> 1. git-replay now updates the ref, simplifying my git-reply-checkout script. Someone on this list recommended it to me in response to an issue I had a long time ago, and I think I can safely say that git-replay is an invaluable tool. Thanks!
> 2. git-pull often fails with a dangling remote ref error, and fails to update the current branch (main, in my case): the workaround is to reset-hard to origin/main. I'm not sure if this is a GitHub issue, or a bug in core git: I've never encountered this behavior on older versions of git, with the exception of submodules.
> 3. git-diff sometimes exits with 0 code without printing a diff, even though the worktree is dirty: the workaround is to run it again. I've never encountered this behavior on older versions of git, and I think it might be a subtle race in core git.
> 4. `git checkout -` sometimes fails with an invalid ref error after a pull, where the previous branch is a local branch. I don't know if this is due to a background git-gc with some behavior change, but I never encountered this behavior on older versions without an operation that would cause this.
> 
> Before digging further to find the root cause, I'd like to know if there is some explanation I'm missing, or if these are known issues?

I haven't heard of any of these things and I usually follow bug reports
to the list fairly closely.  I also use Homebrew's Git on my work Mac
using macOS 26 and haven't run into any of these things, either.  I feel
like my colleagues would have mentioned this, too, and I haven't heard
about any such thing anywhere, including in our Git users channel.

Do you maybe have some sort of security software running on your Mac?
That seems like a thing that could cause items 2–4.  Also, are you
having any sort of other disk, hardware, or other problems where files
sometimes go missing or don't have the expected content?

Are you using files or reftable as the ref backend for your repositories
(or a combination of both)?  If you're using the files backend, does
switch to reftable (`git refs migrate --ref-format=reftable`) fix the
problem or change the behaviour?
-- 
brian m. carlson (they/them)
Toronto, Ontario, CA

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Re: User report on git 2.55.0

[Ramkumar Ramachandra]

brian m. carlson wrote:
> On 2026-09-04 at 18:05:43, Ramkumar Ramachandra wrote:
>> Hi,
>> 
>> I recently bumped to the latest version of git on macOS via homebrew, and here's what I've noticed:
>> 
>> 1. git-replay now updates the ref, simplifying my git-reply-checkout script. Someone on this list recommended it to me in response to an issue I had a long time ago, and I think I can safely say that git-replay is an invaluable tool. Thanks!
>> 2. git-pull often fails with a dangling remote ref error, and fails to update the current branch (main, in my case): the workaround is to reset-hard to origin/main. I'm not sure if this is a GitHub issue, or a bug in core git: I've never encountered this behavior on older versions of git, with the exception of submodules.
>> 3. git-diff sometimes exits with 0 code without printing a diff, even though the worktree is dirty: the workaround is to run it again. I've never encountered this behavior on older versions of git, and I think it might be a subtle race in core git.
>> 4. `git checkout -` sometimes fails with an invalid ref error after a pull, where the previous branch is a local branch. I don't know if this is due to a background git-gc with some behavior change, but I never encountered this behavior on older versions without an operation that would cause this.
>> 
>> Before digging further to find the root cause, I'd like to know if there is some explanation I'm missing, or if these are known issues?
>
> I haven't heard of any of these things and I usually follow bug reports
> to the list fairly closely.  I also use Homebrew's Git on my work Mac
> using macOS 26 and haven't run into any of these things, either.  I feel
> like my colleagues would have mentioned this, too, and I haven't heard
> about any such thing anywhere, including in our Git users channel.

Hm, perhaps what's somewhat unique in my case is the scale repository? I only observe this on llvm/llvm-project.git on GitHub, which gets 200+ updates over a 24-hour window, and measures 30mn+ lines of code. Also, as a former contributor to git, I have the habit of concurrently running git commands or terminating them early when my muscle memory tells me that it's safe: it's hard to pinpoint what exactly, but I don't think git will ever leave the repository in a broken state (I know to clean up state markers by hand).

> Do you maybe have some sort of security software running on your Mac?

I think it's clean, but it's still a possibility that the workplace installed something recently: I don't see any other strange symptoms with any other software though, and everything seems to working reliably? Perhaps the most common task: I run llvm tests over 30 times a day on different changes, and it never reports any spurious failures? I will nevertheless ask the IT team at my workplace if something that I can't see was installed. I don't use my personal laptop for llvm work, so doing that comparison is not possible.

> That seems like a thing that could cause items 2–4.  Also, are you
> having any sort of other disk, hardware, or other problems where files
> sometimes go missing or don't have the expected content?

I suspected that as well, but doesn't seem to be the case: the laptop is less than a year old, and I haven't observed even a hint of hardware problems?

> Are you using files or reftable as the ref backend for your repositories
> (or a combination of both)?  If you're using the files backend, does
> switch to reftable (`git refs migrate --ref-format=reftable`) fix the
> problem or change the behaviour?

Thanks for the tip! I was using loose refs, but just migrated to reftables: will report back in a couple of weeks or so either way.

p.s. There was a small error in my previous email. The update to git-replay I mentioned as the first item happened one or two versions ago: I remember updating my git-replay-checkout script around February or so, while 2.55.0 was released just over a month ago.

Warm regards,
Ram

Re: User report on git 2.55.0

[Ramkumar Ramachandra]

Ramkumar Ramachandra wrote:
> brian m. carlson wrote:
>> Do you maybe have some sort of security software running on your Mac?
>
> I think it's clean, but it's still a possibility that the workplace 
> installed something recently: I don't see any other strange symptoms 
> with any other software though, and everything seems to working 
> reliably? Perhaps the most common task: I run llvm tests over 30 times 
> a day on different changes, and it never reports any spurious failures? 
> I will nevertheless ask the IT team at my workplace if something that I 
> can't see was installed. I don't use my personal laptop for llvm work, 
> so doing that comparison is not possible.

I found the malware: it's Crowdstrike Falcon x(

Case closed.

Warm regards,
Ram

Re: User report on git 2.55.0

[Ben Knoble]

> Le 4 sept. 2026 à 19:13, Ramkumar Ramachandra <r@artagnon.com> a écrit :
> 
> Ramkumar Ramachandra wrote:
>> brian m. carlson wrote:
>>> Do you maybe have some sort of security software running on your Mac?
>> 
>> I think it's clean, but it's still a possibility that the workplace
>> installed something recently: I don't see any other strange symptoms
>> with any other software though, and everything seems to working
>> reliably? Perhaps the most common task: I run llvm tests over 30 times
>> a day on different changes, and it never reports any spurious failures?
>> I will nevertheless ask the IT team at my workplace if something that I
>> can't see was installed. I don't use my personal laptop for llvm work,
>> so doing that comparison is not possible.
> 
> I found the malware: it's Crowdstrike Falcon x(

Hear hear. I haven’t observed issues with Git (based on next, I believe) I compile and install to $HOME at work, but I think we also use CrowdStrike Falcon. I’ll keep my eye out, but the scale of repos I deal with on that ‘puter doesn’t come close. 

Re: User report on git 2.55.0

[Ramkumar Ramachandra]

Ben Knoble wrote:
>> Le 4 sept. 2026 à 19:13, Ramkumar Ramachandra <r@artagnon.com> a écrit :
>> 
>> Ramkumar Ramachandra wrote:
>>> brian m. carlson wrote:
>>>> Do you maybe have some sort of security software running on your Mac?
>>> 
>>> I think it's clean, but it's still a possibility that the workplace
>>> installed something recently: I don't see any other strange symptoms
>>> with any other software though, and everything seems to working
>>> reliably? Perhaps the most common task: I run llvm tests over 30 times
>>> a day on different changes, and it never reports any spurious failures?
>>> I will nevertheless ask the IT team at my workplace if something that I
>>> can't see was installed. I don't use my personal laptop for llvm work,
>>> so doing that comparison is not possible.
>> 
>> I found the malware: it's Crowdstrike Falcon x(
>
> Hear hear. I haven’t observed issues with Git (based on next, I 
> believe) I compile and install to $HOME at work, but I think we also 
> use CrowdStrike Falcon. I’ll keep my eye out, but the scale of repos I 
> deal with on that ‘puter doesn’t come close.

I found the exact issue: Falcon is scanning every file on my machine -- since the volume of changes on the LLVM repository is very large, the high-speed internet, high-speed filesystem, high-speed compilation, and git is are are constantly racing against Falcon's slow scanning, and failing; that's why the problems are random and non-reproducible.

R.