Python Windows Long Path Problems

win_python_long_path_errors.md

Problems with Windows Long Path in Python

It seems there is a limit in Windows API paths, that is causing the Digital Preservation script to fail with the message of "file not found"

>>> source_dir = Path(r"G:\GSDC High Res Photos\2023-GSDC\2023-05-31-Day 2\2023-05-31-1030-1200-Using reconciliation and migration to drive the development of more sustainable and equitable societies")
>>> dest_dir = Path(r"E:\KAUST_ARCHIVES\009_COMMUNICATIONS_AND_PUBLIC_RELATIONS\001_GLOBAL_BRANDING_AND_COMMUNICATIONS\009_001_0018\mg_test")
>>> copytree(source_dir, dest_dir)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.10_3.10.3056.0_x64__qbz5n2kfra8p0\lib\shutil.py", line 559, in copytree
    return _copytree(entries=entries, src=src, dst=dst, symlinks=symlinks,
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.10_3.10.3056.0_x64__qbz5n2kfra8p0\lib\shutil.py", line 513, in _copytree
    raise Error(errors)
shutil.Error: [('G:\\GSDC High Res Photos\\2023-GSDC\\2023-05-31-Day 2\\2023-05-31-1030-1200-Using reconciliation and migration to drive the development of more sustainable and equitable societies\\2023-05-31-1030-1200-Using reconciliation and migration to drive the development of more sustainable and equitable societies-001.JPG', 'E:\\KAUST_ARCHIVES\\009_COMMUNICATIONS_AND_PUBLIC_RELATIONS\\001_GLOBAL_BRANDING_AND_COMMUNICATIONS\\009_001_0018\\mg_test\\2023-05-31-1030-1200-Using reconciliation and migration to drive the development of more sustainable and equitable societies-001.JPG', "[Errno 2] No such file or directory

The path of the files in source_dir are bigger than the 260 characters limit:

>>> for child in source_dir.iterdir():
...     print(len(str(child)))
...
308
308
(...)

To enable long paths in Windows API it's necessary to change a key in Windows Registry

Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem\LongPathsEnabled

Currently this is not enabled in FRED

Key Name:          HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem
Class Name:        <NO CLASS>
Last Write Time:   4/18/2021 - 3:44 AM
(...)
Value 2
  Name:            LongPathsEnabled
  Type:            REG_DWORD
  Data:            0 <------ Not enabled

To fix the problem we will need to enable the LongPathsEnabled and reboot FRED.