diff --git a/aggregator.go b/aggregator.go
index 9f8da70..e9a0d95 100644
--- a/aggregator.go
+++ b/aggregator.go
@@ -158,7 +158,12 @@ func (a *aggregator) aggregate(t time.Time) {
 			for i, m := range msgs {
 				tasks[i] = NewTask(m.Type, m.Payload)
 			}
-			aggregatedTask := a.ga.Aggregate(gname, tasks)
+			aggregatedTask, err := a.ga.Aggregate(gname, tasks)
+			if err != nil {
+				a.logger.Errorf("Failed to aggregate tasks: queue=%q, group=%q, setID=%q: %v",
+					qname, gname, aggregationSetID, err)
+				continue
+			}
 			ctx, cancel := context.WithDeadline(context.Background(), deadline)
 			if _, err := a.client.EnqueueContext(ctx, aggregatedTask, Queue(qname)); err != nil {
 				a.logger.Errorf("Failed to enqueue aggregated task (queue=%q, group=%q, setID=%q): %v",
diff --git a/aggregator_test.go b/aggregator_test.go
index ccce306..3c42c94 100644
--- a/aggregator_test.go
+++ b/aggregator_test.go
@@ -26,7 +26,7 @@ func TestAggregator(t *testing.T) {
 		gracePeriod      time.Duration
 		maxDelay         time.Duration
 		maxSize          int
-		aggregateFunc    func(gname string, tasks []*Task) *Task
+		aggregateFunc    func(gname string, tasks []*Task) (*Task, error)
 		tasks            []*Task       // tasks to enqueue
 		enqueueFrequency time.Duration // time between one enqueue event to another
 		waitTime         time.Duration // time to wait
@@ -38,8 +38,8 @@ func TestAggregator(t *testing.T) {
 			gracePeriod: 1 * time.Second,
 			maxDelay:    0, // no maxdelay limit
 			maxSize:     0, // no maxsize limit
-			aggregateFunc: func(gname string, tasks []*Task) *Task {
-				return NewTask(gname, nil, MaxRetry(len(tasks))) // use max retry to see how many tasks were aggregated
+			aggregateFunc: func(gname string, tasks []*Task) (*Task, error) {
+				return NewTask(gname, nil, MaxRetry(len(tasks))), nil // use max retry to see how many tasks were aggregated
 			},
 			tasks: []*Task{
 				NewTask("task1", nil, Group("mygroup")),
@@ -64,8 +64,8 @@ func TestAggregator(t *testing.T) {
 			gracePeriod: 2 * time.Second,
 			maxDelay:    4 * time.Second,
 			maxSize:     0, // no maxsize limit
-			aggregateFunc: func(gname string, tasks []*Task) *Task {
-				return NewTask(gname, nil, MaxRetry(len(tasks))) // use max retry to see how many tasks were aggregated
+			aggregateFunc: func(gname string, tasks []*Task) (*Task, error) {
+				return NewTask(gname, nil, MaxRetry(len(tasks))), nil // use max retry to see how many tasks were aggregated
 			},
 			tasks: []*Task{
 				NewTask("task1", nil, Group("mygroup")), // time 0
@@ -91,8 +91,8 @@ func TestAggregator(t *testing.T) {
 			gracePeriod: 1 * time.Minute,
 			maxDelay:    0, // no maxdelay limit
 			maxSize:     5,
-			aggregateFunc: func(gname string, tasks []*Task) *Task {
-				return NewTask(gname, nil, MaxRetry(len(tasks))) // use max retry to see how many tasks were aggregated
+			aggregateFunc: func(gname string, tasks []*Task) (*Task, error) {
+				return NewTask(gname, nil, MaxRetry(len(tasks))), nil // use max retry to see how many tasks were aggregated
 			},
 			tasks: []*Task{
 				NewTask("task1", nil, Group("mygroup")),
diff --git a/server.go b/server.go
index 1b98a95..cfe1ca5 100644
--- a/server.go
+++ b/server.go
@@ -239,15 +239,15 @@ type GroupAggregator interface {
 	// Use NewTask(typename, payload, opts...) to set any options for the aggregated task.
 	// The Queue option, if provided, will be ignored and the aggregated task will always be enqueued
 	// to the same queue the group belonged.
-	Aggregate(group string, tasks []*Task) *Task
+	Aggregate(group string, tasks []*Task) (*Task, error)
 }
 
 // The GroupAggregatorFunc type is an adapter to allow the use of  ordinary functions as a GroupAggregator.
 // If f is a function with the appropriate signature, GroupAggregatorFunc(f) is a GroupAggregator that calls f.
-type GroupAggregatorFunc func(group string, tasks []*Task) *Task
+type GroupAggregatorFunc func(group string, tasks []*Task) (*Task, error)
 
 // Aggregate calls fn(group, tasks)
-func (fn GroupAggregatorFunc) Aggregate(group string, tasks []*Task) *Task {
+func (fn GroupAggregatorFunc) Aggregate(group string, tasks []*Task) (*Task, error) {
 	return fn(group, tasks)
 }