incusd/instance: Fallback to stateless start when no state available

Signed-off-by: Stéphane Graber <[email protected]>

internal/server/instance/drivers/driver_lxc.go

@@ -2425,13 +2425,7 @@ func (d *lxc) Start(stateful bool) error {
 	}
 
 	// If stateful, restore now.
-	if stateful {
-		if !d.stateful {
-			err = fmt.Errorf("Instance has no existing state to restore")
-			op.Done(err)
-			return err
-		}
-
+	if stateful && d.stateful {
 		d.logger.Info("Restoring stateful checkpoint")
 
 		criuMigrationArgs := instance.CriuMigrationArgs{

internal/server/instance/drivers/driver_qemu.go

@@ -1438,13 +1438,12 @@ func (d *qemu) start(stateful bool, op *operationlock.InstanceOperation) error {
 
 	// If stateful, restore now.
 	if stateful {
-		if !d.stateful {
-			err = fmt.Errorf("Instance has no existing state to restore")
-			op.Done(err)
-			return err
+		if d.stateful {
+			qemuCmd = append(qemuCmd, "-incoming", "defer")
+		} else {
+			// No state to restore, just start as normal.
+			stateful = false
 		}
-
-		qemuCmd = append(qemuCmd, "-incoming", "defer")
 	} else if d.stateful {
 		// Stateless start requested but state is present, delete it.
 		err := os.Remove(d.StatePath())