commaai/openpilot · error · Exception

unable to get max_segment_number. ensure you have access to

Error message

unable to get max_segment_number. ensure you have access to this route or the route is public.

What it means

get_max_seg_number_cached() calls the comma API '/v1/route/<name>' to read 'maxqlog'; any exception (auth failure, 404, network, or a non-int response) is re-raised as a generic Exception with an access hint. SegmentRange operations that expand unbounded ranges (e.g. 'route/3+') need this number.

Source

Thrown at openpilot/tools/lib/route.py:316

    az_prefix = '/'.join(key.split('/')[:3])
    return SegmentName.from_azure_prefix(az_prefix)

  @staticmethod
  def from_azure_prefix(prefix):
    # xxxxxxxx/1111-11-11-11--11-11-11/0
    dongle_id, route_name, segment_num = prefix.split("/")
    return SegmentName(dongle_id + "|" + route_name + "--" + segment_num)


@cache
def get_max_seg_number_cached(sr: 'SegmentRange') -> int:
  try:
    api = CommaApi(get_token())
    max_seg_number = api.get("/v1/route/" + sr.route_name.replace("/", "|"))["maxqlog"]
    assert isinstance(max_seg_number, int)
    return max_seg_number
  except Exception as e:
    raise Exception("unable to get max_segment_number. ensure you have access to this route or the route is public.") from e


class SegmentRange:
  def __init__(self, segment_range: str):
    m = re.fullmatch(RE.SEGMENT_RANGE, segment_range)
    assert m is not None, f"Segment range is not valid {segment_range}"
    self.m = m

  @property
  def route_name(self) -> str:
    return self.m.group("route_name")

  @property
  def dongle_id(self) -> str:
    return self.m.group("dongle_id")

  @property
  def log_id(self) -> str:

View on GitHub (pinned to 516ec1e682)

Solutions

1. Authenticate: run `python tools/lib/auth.py` (or re-login) so get_token() returns a valid token
2. Confirm the route exists and is accessible to your account via cabana/connect
3. Avoid the API call by giving an explicit end segment ('route/2--8' instead of 'route/2--')

Example fix

# before
sr = SegmentRange('b0c9d232|2022-01-01--00-00-00/3+')

# after
sr = SegmentRange('b0c9d232|2022-01-01--00-00-00/3--7')  # explicit end: no max_seg_number lookup

from openpilot.tools.lib.api import CommaApi
from openpilot.tools.lib.auth import get_token

def route_accessible(route_name: str) -> bool:
    try:
        CommaApi(get_token()).get('/v1/route/' + route_name.replace('/', '|'))
        return True
    except Exception:
        return False

try:
    sr = SegmentRange('route/3+')
    _ = get_max_seg_number_cached(sr)
except Exception as e:
    if 'max_segment_number' in str(e):
        sr = SegmentRange('route/3--7')  # explicit end, no API needed

When it happens

Trigger: Using an open-ended SegmentRange like 'route/2--' or route/3+, which must ask the API how many segments exist; calling it for a route your token cannot access, a non-existent route, or while offline.

Common situations: Not logged in (get_token() fails) or expired comma account token; typo'd route name; running tools in an environment without network; private route owned by another user.

Related errors

• error getting events for segment {self._name}
• Call to {path} failed with {r.status_code}
• {error_prefix} failed: {reason}/{subject} - {sd.get('message
• Maximum retries exceeded
• {func.__name__} failed after retry

AI-assisted analysis of commaai/openpilot@516ec1e682 (2026-08-15). Data as JSON: /api/errors/681bd3085adc331f. Report an issue: GitHub.