D4Vinci/Scrapling · error · KeyError

Session '{session_id}' not found

Error message

Session '{session_id}' not found

What it means

SessionManager.pop()/remove() raise KeyError when asked for a session_id that is not registered. The manager keeps sessions in a dict keyed by id; removing an unknown id means it was never added, was already removed, or the id is misspelled.

Source

Thrown at scrapling/spiders/session.py:56

        if lazy:
            self._lazy_sessions.add(session_id)

        return self

    def remove(self, session_id: str) -> None:
        """Removes a session.

        :param session_id: ID of session to remove
        """
        _ = self.pop(session_id)

    def pop(self, session_id: str) -> Session:
        """Remove and returns a session.

        :param session_id: ID of session to remove
        """
        if session_id not in self._sessions:
            raise KeyError(f"Session '{session_id}' not found")

        session = self._sessions.pop(session_id)
        if session_id in self._lazy_sessions:
            self._lazy_sessions.remove(session_id)

        if session and self._default_session_id == session_id:
            self._default_session_id = next(iter(self._sessions), None)

        return session

    @property
    def default_session_id(self) -> str:
        if self._default_session_id is None:
            raise RuntimeError("No sessions registered")
        return self._default_session_id

    @property
    def session_ids(self) -> list[str]:

View on GitHub (pinned to 5d213a2d47)

Solutions

1. Guard removals: if session_id in manager.session_ids: manager.remove(session_id).
2. Use session_ids (or a try/except KeyError) to make teardown idempotent.
3. Centralize session-id constants in one place instead of repeating string literals.

Example fix

# before
manager.remove('htp')  # KeyError (typo)

# after
if 'http' in manager.session_ids:
    manager.remove('http')

def safe_remove(manager, session_id: str) -> bool:
    if session_id in manager.session_ids:
        manager.remove(session_id)
        return True
    return False

from contextlib import suppress

with suppress(KeyError):
    manager.remove(session_id)  # idempotent teardown

When it happens

Trigger: manager.remove('http') when only 'browser' was registered; double-cleanup code that removes the same session in teardown and again in an outer finally block.

Common situations: Teardown routines running twice (finally + atexit); typos in session ids; removing a session that a failed setup step never actually registered.

Related errors

• Session '{session_id}' not found. Available: {available}
• {self.__class__.__name__}.configure_sessions() did not add a
• Session '{session_id}' not found. Use list_sessions to see a
• Session '{session_id}' is no longer alive. Open a new sessio
• Session '{session_id}' is a '{entry.session_type}' session,

AI-assisted analysis of D4Vinci/Scrapling@5d213a2d47 (2026-08-14). Data as JSON: /api/errors/92d0f631513887c8. Report an issue: GitHub.