diff --git a/cmd/dendritejs/main.go b/cmd/dendritejs/main.go
index b8517bf9d..add130aa8 100644
--- a/cmd/dendritejs/main.go
+++ b/cmd/dendritejs/main.go
@@ -209,7 +209,7 @@ func main() {
 	p2pPublicRoomProvider := NewLibP2PPublicRoomsProvider(node)
 
 	rsAPI := roomserver.SetupRoomServerComponent(base, keyRing, federation)
-	eduInputAPI := eduserver.SetupEDUServerComponent(base, cache.New())
+	eduInputAPI := eduserver.SetupEDUServerComponent(base, cache.New(), deviceDB)
 	asQuery := appservice.SetupAppServiceAPIComponent(
 		base, accountDB, deviceDB, federation, rsAPI, transactions.New(),
 	)
diff --git a/internal/sql.go b/internal/sql.go
index c5da03572..4abab4d35 100644
--- a/internal/sql.go
+++ b/internal/sql.go
@@ -123,14 +123,14 @@ type TransactionWriter struct {
 // transactionWriterTask represents a specific task.
 type transactionWriterTask struct {
 	db   *sql.DB
-	f    func(txn *sql.Tx)
-	wait chan struct{}
+	f    func(txn *sql.Tx) error
+	wait chan error
 }
 
 // Do queues a task to be run by a TransactionWriter. The function
 // provided will be ran within a transaction as supplied by the
 // database parameter. This will block until the task is finished.
-func (w *TransactionWriter) Do(db *sql.DB, f func(txn *sql.Tx)) {
+func (w *TransactionWriter) Do(db *sql.DB, f func(txn *sql.Tx) error) error {
 	if w.todo == nil {
 		w.todo = make(chan transactionWriterTask)
 	}
@@ -140,10 +140,10 @@ func (w *TransactionWriter) Do(db *sql.DB, f func(txn *sql.Tx)) {
 	task := transactionWriterTask{
 		db:   db,
 		f:    f,
-		wait: make(chan struct{}),
+		wait: make(chan error, 1),
 	}
 	w.todo <- task
-	<-task.wait
+	return <-task.wait
 }
 
 // run processes the tasks for a given transaction writer. Only one
@@ -156,9 +156,8 @@ func (w *TransactionWriter) run() {
 	}
 	defer w.running.Store(false)
 	for task := range w.todo {
-		_ = WithTransaction(task.db, func(txn *sql.Tx) error {
-			task.f(txn)
-			return nil
+		task.wait <- WithTransaction(task.db, func(txn *sql.Tx) error {
+			return task.f(txn)
 		})
 		close(task.wait)
 	}
diff --git a/syncapi/storage/shared/syncserver.go b/syncapi/storage/shared/syncserver.go
index 841f2d536..86747f874 100644
--- a/syncapi/storage/shared/syncserver.go
+++ b/syncapi/storage/shared/syncserver.go
@@ -1078,8 +1078,8 @@ func (d *Database) StoreNewSendForDeviceMessage(
 	}
 	// Delegate the database write task to the SendToDeviceWriter. It'll guarantee
 	// that we don't lock the table for writes in more than one place.
-	d.SendToDeviceWriter.Do(d.DB, func(txn *sql.Tx) {
-		err = d.AddSendToDeviceEvent(
+	err = d.SendToDeviceWriter.Do(d.DB, func(txn *sql.Tx) error {
+		return d.AddSendToDeviceEvent(
 			ctx, txn, userID, deviceID, string(j),
 		)
 	})
@@ -1143,18 +1143,18 @@ func (d *Database) CleanSendToDeviceUpdates(
 	// If we need to write to the database then we'll ask the SendToDeviceWriter to
 	// do that for us. It'll guarantee that we don't lock the table for writes in
 	// more than one place.
-	d.SendToDeviceWriter.Do(d.DB, func(txn *sql.Tx) {
+	err = d.SendToDeviceWriter.Do(d.DB, func(txn *sql.Tx) error {
 		// Delete any send-to-device messages marked for deletion.
 		if e := d.SendToDevice.DeleteSendToDeviceMessages(ctx, txn, toDelete); e != nil {
-			err = fmt.Errorf("d.SendToDevice.DeleteSendToDeviceMessages: %w", e)
-			return
+			return fmt.Errorf("d.SendToDevice.DeleteSendToDeviceMessages: %w", e)
 		}
 
 		// Now update any outstanding send-to-device messages with the new sync token.
 		if e := d.SendToDevice.UpdateSentSendToDeviceMessages(ctx, txn, token.String(), toUpdate); e != nil {
-			err = fmt.Errorf("d.SendToDevice.UpdateSentSendToDeviceMessages: %w", err)
-			return
+			return fmt.Errorf("d.SendToDevice.UpdateSentSendToDeviceMessages: %w", err)
 		}
+
+		return nil
 	})
 	return
 }