nodejs/node · error · Exception

Could not find pattern matching %s

Error message

Could not find pattern matching %s

What it means

Raised by get_napi_version() in tools/getnapibuildversion.py after it opens ../src/node_version.h (relative to the script) and iterates every line without finding one matching '^#define NODE_API_SUPPORTED_VERSION_MAX'. The file was readable, but the expected N-API version macro is absent. This script feeds Node's native-addon build system the maximum stable N-API version, so a missing macro means the build cannot pick an N-API target.

Source

Thrown at tools/getnapibuildversion.py:22

def get_napi_version():
  napi_version_h = os.path.join(
    os.path.dirname(__file__),
    '..',
    'src',
    'node_version.h')

  f = open(napi_version_h)

  regex = '^#define NODE_API_SUPPORTED_VERSION_MAX'

  for line in f:
    if re.match(regex, line):
      napi_version = line.split()[2]
      return napi_version

  raise Exception('Could not find pattern matching %s' % regex)


if __name__ == '__main__':
  print(get_napi_version())

View on GitHub (pinned to 1b2de5e052)

Solutions

1. Open src/node_version.h and confirm a line exactly like '#define NODE_API_SUPPORTED_VERSION_VERSION_MAX 9' exists; if missing, update the Node checkout.
2. Ensure the script is run from the correct repo root so '../src/node_version.h' resolves to the real Node header (check `os.path.dirname(__file__)/../src/node_version.h`).
3. If you maintain a fork that renamed the macro, patch the regex at getnapibuildversion.py:15 to match the new name.
4. Pin to a Node version known to ship the macro rather than a stripped/custom header.

Example fix

// before
regex = '^#define NODE_API_SUPPORTED_VERSION_MAX'

// after (also accept a legacy/renamed macro, fail loudly with file context)
regex = r'^#\s*define\s+NODE_API_SUPPORTED_VERSION_MAX\b'
if not os.path.exists(napi_version_h):
  raise Exception('node_version.h not found at %s' % napi_version_h)

import os, re
h = os.path.join(os.path.dirname(__file__), 'src', 'node_version.h')
if not os.path.exists(h):
    raise SystemExit('node_version.h missing at %s' % h)
found = any(re.match(r'^#define\s+NODE_API_SUPPORTED_VERSION_MAX\b', line)
            for line in open(h))
if not found:
    raise SystemExit('macro not present; update Node checkout')

def has_napi_macro(header_path: str) -> bool:
    import re
    if not os.path.isfile(header_path):
        return False
    pat = re.compile(r'^#define\s+NODE_API_SUPPORTED_VERSION_MAX\b')
    return any(pat.match(line) for line in open(header_path))

try:
    napi = get_napi_version()
except Exception as e:
    # header present but macro absent -> wrong/old Node source
    raise SystemExit('Cannot determine N-API version: %s. Check src/node_version.h.' % e)

When it happens

Trigger: Calling `python tools/getnapibuildversion.py` (or having node-gyp/gyp invoke it during a native module build) when the checked-out src/node_version.h predates N-API, has been stripped, or the script is run from a tree where src/ is not the matching Node source. The regex matches only a literal '#define NODE_API_SUPPORTED_VERSION_MAX' line; any reformatting (e.g. extra spaces, renamed macro) also misses.

Common situations: Building against an old Node checkout (pre-8.6.0) that never had the macro; running the tool standalone outside a Node source tree; vendoring only part of Node's src/; a downstream fork that renamed the macro.

Related errors

• --enable-v8windbg is incompatible with --without-bundled-v8.
• --v8-enable-hugepage is supported only on linux.
• Only one of the --v8-enable-object-print or --v8-disable-obj
• Only one of the --v8-enable-temporal-support or --v8-disable
• Unexpected error while reading %s: %s

AI-assisted analysis of nodejs/node@1b2de5e052 (2026-08-13). Data as JSON: /api/errors/05ad4c5f12527dd5. Report an issue: GitHub.