Git has a limit of 4096 characters for a filename, except on Windows when Git is compiled with msys. It uses an older version of the Windows API and there's a limit of 260 characters for a filename.
So as far as I understand this, it's a limitation of msys and not of Git. You can read the details here: https://github.com/msysgit/git/pull/110
You can circumvent this by using another Git client on Windows or set core.longpaths to true as explained in other answers.
git config --system core.longpaths true
Git is build as a combination of scripts and compiled code. With the above change some of the scripts might fail. That's the reason for core.longpaths not to be enabled by default.
The windows documentation at https://docs.microsoft.com/en-us/windows/desktop/fileio/naming-a-file has some more information:
Starting in Windows 10, version 1607, MAX_PATH limitations have been removed from common Win32 file and directory functions. However, you must opt-in to the new behavior.
A registry key allows you to enable or disable the new long path behavior. To enable long path behavior set the registry key at HKLM\SYSTEM\CurrentControlSet\Control\FileSystem LongPathsEnabled (Type: REG_DWORD)
The limitation to 260 chars in a path is not specific to MSYS, it's a general Windows API imitation. This can be worked around by using Unicode paths, but that has other drawbacks, which is why
core.longpathsis not enabled by default. Also note that Git for Windows it not compiled against MSYS. Instead, it's a native Windows application that comes with a stripped-down MSYS environment.@sschuberth: Are there any drawbacks other than lack of compatibility with programs that do not support long paths?
@JAB Another drawback is that long paths always have to be absolute; relative paths are not supported. For further details please see here.
Or as a quick fix, just try checkout your repo to C:/ on windows thus reducing number of folder path characters.
FYI, by the time now the issue still persists. We might want to consider continuing development on a real operating system...