Filename too Long error during Git operations

Problem

Filename too long error occurring when running Git commands over a repository or branch that has fully-qualified file paths (including a build tool’s working directory) over 260 characters in length.

For example (from Atlassian Bamboo):

Merge command error: com.atlassian.bamboo.repository.RepositoryException: DDM-CCI0-3: Checkout to revision 
6e71c27c4d11665f589d1d01d88711fc4b9ae29a has failed.command ['C:\Program Files\Git\cmd\git.exe' checkout -f 
develop] failed with code 1. Working directory was [D:\MettleCI\AppData\Bamboo\xml-data\build-dir\serverSide
\DDM-CCI0-3\mergeWorkspace]., stderr: Branch 'develop' set up to track remote branch 'develop' from 'origin'.
error: unable to create file datastage/Jobs/CCIS_GENERAL/MAIN/020_EXTRACTS/080_ASSESSMENT_ANSWER/080_ACAP/CACO_
ASSESSMENT/CG_ACAP_ACAPCareCo_Assessment_Answer_030_Filter_AssessmentAnswer_Into_ACAPCareCo_Templates_NEW.isx:
Filename too long

Solution

The change in Windows and Git behaviour detailed below will allow paths up to 4096 characters long.

NOTE

From Microsoft…

"Starting in Windows 10, version 1607, (and Windows 2016 Server) MAX_PATH limitations have been removed from common Win32 file and directory functions. However, you must opt-in to the new behaviour."

Here's how to enable Windows long file paths in the Windows registry:

The Easy Way

The easy way is to use regedit.exe to modify the registry key which enables or disables the new long path behaviour. To enable long path behaviour set the following registry key:
HKLM\SYSTEM\CurrentControlSet\Control\FileSystem LongPathsEnabled (Type: REG_DWORD) = 1

The Longer Way

Open Group Policy Editor by typing the following command in a Windows command window.
gpedit.msc
Navigate to the following directory: Local Computer Policy → Computer Configuration → Administrative Templates → System → Filesystem
Double-click the Enable NTFS long paths option.
Choose Enabled
Click Apply and OK

Final Step: Update the Git Configuration

Enable long paths on the Git client installed on your Bamboo Host (this will be automatically added to your git config files):