MISSING_CHECKPOINTER: persistence features need a checkpointer on compile()

MISSING_CHECKPOINTER

from langgraph.checkpoint.memory import InMemorySaver
from langgraph.graph import StateGraph

checkpointer = InMemorySaver()
graph = builder.compile(checkpointer=checkpointer)

Functional API:

from langgraph.func import entrypoint

@entrypoint(checkpointer=checkpointer)
def workflow(messages: list) -> str:
    ...

Rules

• Every persistence feature (per-thread history, interrupts, time travel) requires the checkpointer. There is no default.
• InMemorySaver is for dev and tests. For local durable runs use SqliteSaver (langgraph-checkpoint-sqlite); for production use PostgresSaver (langgraph-checkpoint-postgres).
• Async graphs need AsyncSqliteSaver / AsyncPostgresSaver.
• In JS this is the MISSING_CHECKPOINTER error code.

Error catalog entry grounded in the official MISSINGCHECKPOINTER error page and checkpointers docs, verified 2026-09-26. Error page: https://docs.langchain.com/oss/python/langgraph/errors/MISSINGCHECKPOINTER ; checkpointers: https://docs.langchain.com/oss/python/langgraph/checkpointers