How to change the default 256 character path limitation (MAX_PATH) in Windows 10

Autodesk Support

Mar 18, 2025

Products and versions covered

Issue:

How to change the default 256 character path length limitation (MAX_PATH) in Windows 10.

Environment:

Windows 10 (1607) and newer versions.

Causes:

By default, Windows uses a path length limitation (MAX_PATH) of 256 characters: Naming Files, Paths, and Namespaces.

Solution:

Autodesk products, like Inventor, have a limit of 256 characters for file paths because of the way Windows works. Windows has a rule that file paths (the location of a file on your computer) can't be longer than 256 characters. This rule affects Autodesk products because they use Windows to manage files. Even though you can change this limit in Windows settings, it doesn't mean all programs will work with longer paths. Microsoft made this change because some tools need longer paths, but many programs still follow the old rule.


Starting in Windows 10 (Version 1607), the MAX_PATH limitations have been removed from Common Win32 file and directory functions. To use the new extended path behavior, you must opt-in by using a registry key change.

Warning!
Problems caused by improperly editing the Windows registry could render your computer operating system unusable. Microsoft provides a wealth of critical information that you need to know about the registry in the Microsoft Knowledge Base. Use the Microsoft Registry Editor only at your own risk and only after backing up the registry as outlined for your operating system in the Microsoft article How to back up and restore the registry in Windows and in the related solution How to back up the system registry. Additional information about the registry is also contained in the Help topics in the Microsoft Registry Editor.

To enable the long path behavior in Windows 10:

  1. Go to Windows Start and type REGEDIT.
  2. Choose the Registry Editor.
  3. In the Registry Editor, navigate to the following location: at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem.
  4. Select the entry named: LongPathsEnabled. 
Note: If the registry key does not exist, the entry can also be added by doing the following:
  1. With the FileSystem folder selected, right-click in the empty space of the Name column where the registry keys are located.
  2. Select New.
  3. Choose the DWORD (32-bit) Value.
Making changes in Registry Editor
  1. Right-click the newly added key and choose Rename.
  2. Name the key LongPathsEnabled.
  3. Press Enter.
  1. Double-click on the LongPathsEnabled entry to open the key. 
  2. In the Value data field, enter a value of 1. This will enable to long paths option.
The registry key's value will be cached by the system (per process) after the first call to an affected Win32 file or directory function. The registry key will not be reloaded during the lifetime of the process. In order for all apps on the system to recognize the value of the key, a machine restart might be required because some processes may have started before the key was set.

Additionally, the registry key can also be controlled via the Group Policy in Computer Configuration > Administrative Templates > System > Filesystem > Enable NTFS long paths.

Enable NTFS long paths (Group policy) 

Products:

All Desktop Products;

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