How do you handle long file paths (over 260 characters) in .NET Framework and .NET Core?

Question

ICSM Computer · Answer

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	o\your\file.txt";
File.ReadAllText(longPath);
Requirements:
Must use full (absolute) paths.Works only with local paths, not relative paths.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:
Open gpedit.mscNavigate to:
Computer Configuration andgt; Administrative Templates andgt; System andgt; FilesystemEnable: 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
Prefer .NET Core or later for better long path support.Avoid long path issues by keeping directory structures flat when possible.Use Path.GetFullPath() to debug unexpected length problems.

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How do you handle long file paths (over 260 characters) in .NET Framework and .NET Core?

ICSM Computer

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1 Answers

Why the 260 Character Limit?

.NET Framework (≤ 4.6.2)

Problem:

Workaround:

Requirements:

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

Ensure Windows long paths are enabled:

Then use normally:

Tips

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