pathwaycom/pathway · error · ValueError

Cannot enable interactive mode

Error message

Cannot enable interactive mode

What it means

enable_interactive_mode() refuses (ValueError 'Cannot enable interactive mode') when the global graph G.global_scope is not empty, i.e. some tables/operators were already built. Interactive mode must be switched on before any pathway computation is defined; it is also experimental and emits a warning. If a controller already exists it is returned idempotently instead of raising.

Source

Thrown at python/pathway/internals/interactive.py:213

def is_interactive_mode_enabled() -> bool:
    graph = parse_graphs.G

    return graph.interactive_mode_controller is not None


def enable_interactive_mode() -> InteractiveModeController:
    warnings.warn("interactive mode is experimental", stacklevel=2)

    graph = parse_graphs.G

    if graph.interactive_mode_controller is not None:
        return graph.interactive_mode_controller

    if not graph.global_scope.is_empty():
        # XXX: is this a correct test?
        raise ValueError("Cannot enable interactive mode")

    import logging

    logging.basicConfig(level=logging.INFO)

    graph.interactive_mode_controller = InteractiveModeController(
        _pathway_internal=True
    )
    return graph.interactive_mode_controller

View on GitHub (pinned to fa2f74a464)

Solutions

1. Call pw.internals.enable_interactive_mode() as the first pathway statement in the notebook/session, before defining any connectors or tables
2. Restart the Python kernel / process to clear G.global_scope, then enable interactive mode first
3. Move pipeline-building imports/code after the enable_interactive_mode() call

Example fix

# before
import pathway as pw
t = pw.debug.table_from_markdown('a\n1')
pw.internals.enable_interactive_mode()  # ValueError

# after
import pathway as pw
pw.internals.enable_interactive_mode()  # enable first
t = pw.debug.table_from_markdown('a\n1')

import pathway as pw

def ensure_interactive():
    if not pw.internals.parse_graphs.G.global_scope.is_empty():
        raise RuntimeError("restart kernel; interactive mode must be enabled before any pathway objects")
    return pw.internals.enable_interactive_mode()

When it happens

Trigger: Calling pw.internals.enable_interactive_mode() (or the recompute()-style entry points that call it) after creating connectors, tables, or any pw.Table in the process; importing a module that defines a pipeline and then enabling interactive mode.

Common situations: Jupyter workflows where earlier cells already built tables; library imports that construct pathway pipelines at import time; second call in a fresh kernel after partial graph construction.

Related errors

• Join received extra kwargs. You probably want to use TableLi
• synchronization_group can only be set once
• Duplicate expression value given for {name}
• Cannot use expression as boolean.
• unit has to be one of s, ms, us, ns but is {unit}.

AI-assisted analysis of pathwaycom/pathway@fa2f74a464 (2026-08-15). Data as JSON: /api/errors/7b3258a0f57af3f4. Report an issue: GitHub.