nodejs/node · error · Exception

is not a file

Error message

{} is not a file

What it means

The adb-d8 file server's second guard: even after a requested path passes the root-prefix check, it must point at a real regular file. If the resolved absolute path is a directory, a broken symlink, or simply doesn't exist, the server raises rather than trying to read it.

Solutions

1. Build the requested artifact on the host first so the file actually exists.
2. Point the device/d8 at the correct file path (check for typos or a missing build-prefix like out/Release/).
3. If using symlinks, ensure the link target is present on the host.

Example fix

# before: request out/Release/d8 but only out/Default/d8 was built
# after: build the Release target, or request out/Default/d8

import os
assert os.path.isfile(filename), f'{filename} is not a regular file; build it or fix the path'

When it happens

Trigger: Raised in FileHandler.handle() when `not os.path.isfile(filename)` is true, immediately after the roots-prefix check passes.

Common situations: Device requests a path that exists in the source layout but wasn't built (e.g. a .so that only appears after `make`); requesting a directory by mistake; a symlink target that's missing on the host; stale d8 payload manifest referencing deleted files.

Related errors

• not in roots
• Could not generate pprof results
• args_file specified multiple times in mixins for
• Cannot generate isolate for
• config file not found at

AI-assisted analysis of nodejs/node@1b2de5e052 (2026-08-13). Data as JSON: /api/errors/e577fc11f1b38710. Report an issue: GitHub.

Appendix: source

Thrown at deps/v8/tools/adb-d8.py:44

import subprocess
import SocketServer # TODO(leszeks): python 3 compatibility

def CreateFileHandlerClass(root_dirs, verbose):
  class FileHandler(SocketServer.BaseRequestHandler):
    def handle(self):
      data = self.request.recv(1024);
      while data[-1] != "\0":
        data += self.request.recv(1024);

      filename = data[0:-1]

      try:
        filename = os.path.abspath(filename)

        if not any(filename.startswith(root) for root in root_dirs):
          raise Exception("{} not in roots {}".format(filename, root_dirs))
        if not os.path.isfile(filename):
          raise Exception("{} is not a file".format(filename))

        if verbose:
          sys.stdout.write("Serving {}\r\n".format(os.path.relpath(filename)))

        with open(filename) as f:
          contents = f.read();
          self.request.sendall(struct.pack("!i", len(contents)))
          self.request.sendall(contents)

      except Exception as e:
        if verbose:
          sys.stderr.write(
            "Request failed ({})\n".format(e).replace('\n','\r\n'))
        self.request.sendall(struct.pack("!i", -1))

  return FileHandler

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