Snowflake Error:
Task Graph Cycle Detected
What does this error mean?
A Snowflake Task DAG definition creates a cycle — a task directly or indirectly depends on itself. Snowflake rejects cyclic task graphs at creation or resume time.
Common causes
- 1Task B lists Task A as a predecessor while Task A also lists Task B (direct cycle)
- 2Multi-task DAG where an indirect chain creates a loop: A → B → C → A
- 3Copy-paste error when building a large task graph that accidentally creates a back-edge
- 4Dynamic task graph generation producing incorrect predecessor assignments
How to fix it
- 1Map out the full task dependency graph and identify the cycle.
- 2Remove the task definition creating the back-edge: `ALTER TASK <task> REMOVE AFTER <predecessor>`.
- 3Rebuild the graph as a true DAG (no cycles) — Snowflake only supports directed acyclic task graphs.
- 4Use `SHOW TASKS IN SCHEMA <schema>` and the `PREDECESSORS` column to inspect the current graph.
- 5Query `SNOWFLAKE.ACCOUNT_USAGE.TASK_HISTORY` to verify which tasks are running and in what order.