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home / developersection / interviews / how do you handle long file paths (over 260 characters) in .net framework and .net core?
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How do you handle long file paths (over 260 characters) in .NET Framework and .NET Core?

Ravi Vishwakarma 1255 16 May 2025
c# c#
Updated 16 May 2025
Ravi Vishwakarma
Ravi Vishwakarma

IT-Hardware & Networking

Ravi Vishwakarma is a dedicated Software Developer with a passion for crafting efficient and innovative solutions. With a keen eye for detail and years of experience, he excels in developing robust software systems that meet client needs. His expertise spans across multiple programming languages and technologies, making him a valuable asset in any software development project.

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1 Answers

Ravi Vishwakarma
Ravi Vishwakarma 16 May 2025
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Handling long file paths (over 260 characters) requires different approaches in .NET Framework vs .NET Core due to historical limitations.

Why the 260 Character Limit?

Windows historically imposed a MAX_PATH limit of 260 characters. In .NET Framework, this limit is enforced unless you use special workarounds. .NET Core and .NET 5+ have better support for long paths by default.

.NET Framework (≤ 4.6.2)

Problem:

By default, paths longer than 260 characters cause an error like:

System.IO.PathTooLongException

Workaround:

Use UNC (long path) prefix: \\?\ before absolute paths.

string longPath = @"\\?\C:\very\long\path\to\your\file.txt";
File.ReadAllText(longPath);

Requirements:

  1. Must use full (absolute) paths.
  2. Works only with local paths, not relative paths.
  3. Limited support in many .NET APIs.

.NET Core / .NET 5+ / .NET 6+

.NET Core and .NET 5+ fully support long paths without requiring \\?\ if the OS supports it and it's enabled.

Ensure Windows long paths are enabled:

  1. Open gpedit.msc
  2. Navigate to:
    Computer Configuration > Administrative Templates > System > Filesystem
  3. Enable: Enable Win32 long paths

Or modify registry:

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem]
"LongPathsEnabled"=dword:00000001

Then use normally:

string path = @"C:\some\very\long\directory\structure\...file.txt";
File.WriteAllText(path, "data");

Tips

  1. Prefer .NET Core or later for better long path support.
  2. Avoid long path issues by keeping directory structures flat when possible.
  3. Use Path.GetFullPath() to debug unexpected length problems.
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