What causes "'{}' is not a directory" in denoland/deno?

Point TEMP/TMP at a real directory: `setx TEMP C:\Users\me\AppData\Local\Temp` (no junction).

denoland/deno · error · AnyError

'{}' is not a directory

Error message

'{}' is not a directory

What it means

The non-Unix (Windows) version of `ensure_secure_temp_parent` validates the temp root with `symlink_metadata` and bails if the path is a symlink/reparse point or is not a real directory. Windows does not get the uid/mode ancestor walk Unix gets; this cheaper check still refuses symlinked temp roots so the temp path cannot be redirected out from under Deno.

Source

Thrown at cli/util/temp.rs:153

        current_uid
      );
    }
    let mode = metadata.mode();
    if mode & 0o022 != 0 && mode & 0o1000 == 0 {
      bail!(
        "temporary directory ancestor '{}' is writable by other users without the sticky bit",
        ancestor.display()
      );
    }
  }
  Ok(())
}

#[cfg(not(unix))]
fn ensure_secure_temp_parent(path: &Path) -> Result<(), AnyError> {
  let metadata = std::fs::symlink_metadata(path)?;
  if metadata.file_type().is_symlink() || !metadata.is_dir() {
    bail!("'{}' is not a directory", path.display());
  }
  Ok(())
}

#[cfg(unix)]
fn create_dir_secure(path: &Path) -> std::io::Result<()> {
  use std::os::unix::fs::DirBuilderExt;

  std::fs::DirBuilder::new().mode(0o700).create(path)
}

#[cfg(not(unix))]
fn create_dir_secure(path: &Path) -> std::io::Result<()> {
  std::fs::create_dir(path)
}

#[cfg(unix)]
fn ensure_secure_temp_dir(path: &Path) -> Result<(), AnyError> {

View on GitHub (pinned to 9ad36f7a2c)

Solutions

Point TEMP/TMP at a real directory: `setx TEMP C:\Users\me\AppData\Local\Temp` (no junction).
Remove the offending link/file: `rmdir <path>` for a junction, `del <path>` for a file.
If you need temp on another drive, create a plain directory there and set TEMP directly to it.

Example fix

# before (PowerShell): TEMP is a junction
(Get-Item $env:TEMP).LinkType    # Junction
deno install                      # error: '<path>' is not a directory

# after
New-Item -ItemType Directory -Force D:\tmp
setx TEMP D:\tmp                  # real directory, not a link
deno install

Defensive patterns

Strategy: validation

Validate before calling

# PowerShell: reject symlinked or non-directory TEMP before running deno
$ti = Get-Item "$env:TEMP" -ErrorAction SilentlyContinue
if ($null -eq $ti -or $ti.LinkType -or -not $ti.PSIsContainer) {
  Write-Error "TEMP is a symlink or not a directory: $env:TEMP"
}

Prevention

Set TEMP/TMP to a plain local directory, never a junction or symlink.
Check launch scripts and policies that redirect TEMP for sandboxing or disk-space reasons.
After moving temp, delete leftover links at the old path.

When it happens

Trigger: On Windows, TEMP/TMP (or TMPDIR) resolving to a symlink/junction to another location, or to a plain file — e.g. `mklink /J` junctions used to relocate TEMP to another drive, or a stale file left at the path.

Common situations: Windows machines redirecting %TEMP% via junction to save SSD space or sandbox browsers; CI images with symlinked temp; users setting TMP to a nonexistent or file path in scripts.

Related errors

AI-assisted analysis of denoland/deno@9ad36f7a2c (2026-08-20). Data as JSON: /api/errors/4a6d644629b21aa5. Report an issue: GitHub.