‘The specified path… is too long’ on Windows

Verified on Windows 11, Node 24.20.0 · OpusMill

reg query "HKLM\SYSTEM\CurrentControlSet\Control\FileSystem" /v LongPathsEnabled

Why this is worth checking

The 260-character MAX_PATH limit is real history and it is what most answers still assume. It has been opt-out since Windows 10 1607. On the machine I am writing this on it is already off, and I measured what that means:

mkdir chain past 260 chars, then write and read a file at the end
  -> 422 characters, read back: hello

reg query "HKLM\SYSTEM\CurrentControlSet\Control\FileSystem" /v LongPathsEnabled
  -> LongPathsEnabled    REG_DWORD    0x1

A 422-character path, created and read without complaint. Nothing was shortened and no \\?\ prefix was used.

This is not a claim that you are fine. The setting is opt-in and plenty of machines still have it at 0x0 — it is likely on here because a developer tool enabled it during installation, which is common but not universal. That is exactly why the useful answer is a command you run rather than a fact you inherit from me.

If it is 0x0

You can turn it on, from an administrator prompt:

reg add "HKLM\SYSTEM\CurrentControlSet\Control\FileSystem" ^
  /v LongPathsEnabled /t REG_DWORD /d 1 /f

Then restart — and know the two catches:

• An application must also opt in, via a manifest entry. Node does. Some older tools in your toolchain may not, and they will keep failing at 260 characters on the same machine.
• cmd.exe is not long-path aware. A build step that shells out can still fail where Node itself succeeds — which looks baffling until you know it.

If you cannot change the machine (a locked-down build agent, a colleague's laptop), the portable answer is to stop generating deep paths: shorten the checkout directory, and prefer C:\src\proj over a nested path under Documents.

If long paths are already on, what else is it?

• A single path component over 255 characters. That limit is the filesystem's and LongPathsEnabled does not lift it. Usually a generated filename — a hash, a base64 blob, a concatenated cache key.
• A tool in the chain that is not long-path aware, including anything invoked through cmd.exe.
• A network or mapped drive, where the limit is the server's and often lower.
• You are not on Windows at all. Linux caps a single component at 255 bytes, and bytes matters — a name of 80 emoji is over the limit while looking short.