What causes "failed to create task in DB: %w" in vxcontrol/pentagi?

Inspect the wrapped DB error — FK violation vs connection vs constraint

failed to create task in DB: %w

Error message

failed to create task in DB: %w

What it means

After generating a title, NewTaskWorker persists the task via CreateTask (DB insert). This error wraps that insert failure. The title was already generated (LLM cost incurred) but nothing is committed; the caller sees the task creation fail.

Source

Thrown at backend/pkg/controller/task.go:72

) (TaskWorker, error) {
	ctx, span := obs.Observer.NewSpan(ctx, obs.SpanKindInternal, "controller.NewTaskWorker")
	defer span.End()

	ctx = tools.PutAgentContext(ctx, database.MsgchainTypePrimaryAgent)

	title, err := flowCtx.Provider.GetTaskTitle(ctx, input)
	if err != nil {
		return nil, fmt.Errorf("failed to get task title: %w", err)
	}

	task, err := flowCtx.DB.CreateTask(ctx, database.CreateTaskParams{
		Status: database.TaskStatusCreated,
		Title:  title,
		Input:  input,
		FlowID: flowCtx.FlowID,
	})
	if err != nil {
		return nil, fmt.Errorf("failed to create task in DB: %w", err)
	}

	flowCtx.Publisher.TaskCreated(ctx, task, []database.Subtask{})

	taskCtx := &TaskContext{
		FlowContext: *flowCtx,
		TaskID:      task.ID,
		TaskTitle:   title,
		TaskInput:   input,
	}
	stc := NewSubtaskController(taskCtx)

	_, err = taskCtx.MsgLog.PutTaskMsg(
		ctx,
		database.MsglogTypeInput,
		taskCtx.TaskID,
		"", // thinking is empty because this is input
		input,

View on GitHub (pinned to ea665308ba)

Solutions

Inspect the wrapped DB error — FK violation vs connection vs constraint
Verify the flow exists before creating tasks against it
Ensure input length fits the DB column definition
Retry CreateTask once the DB issue is resolved

Defensive patterns

Strategy: try-catch

Validate before calling

if flowCtx.FlowID <= 0 { return fmt.Errorf("invalid flow id") }
if len(input) > maxInputLen { return fmt.Errorf("input too large") }

Try / catch

task, err := flowCtx.DB.CreateTask(ctx, params)
if err != nil {
    var pqErr *pq.Error
    if errors.As(err, &pqErr) && pqErr.Code == "23503" {
        return nil, fmt.Errorf("flow %d no longer exists", flowCtx.FlowID)
    }
    return nil, fmt.Errorf("failed to create task in DB: %w", err)
}

Prevention

Check flow existence before creating its tasks
Enforce input length limits at the API boundary
Monitor DB pool and connection errors

When it happens

Trigger: DB connection loss, context cancellation between the LLM call and insert, FlowID referencing a missing flow (FK violation), or column constraint failures on title/input.

Common situations: Flow deleted concurrently while its task was being created (FK violation); Postgres pool exhaustion; oversized input exceeding the input column limit.

Related errors

AI-assisted analysis of vxcontrol/pentagi@ea665308ba (2026-09-01). Data as JSON: /api/errors/ba8fdb9d234f2e5e. Report an issue: GitHub.