diff --git a/src/runtime2/communication.rs b/src/runtime2/communication.rs
index 803db6e48ef4c9ef920d8ffc26b4a86a2d13ad86..6040e234106bbb37dc09f30569661b9890803fcc 100644
--- a/src/runtime2/communication.rs
+++ b/src/runtime2/communication.rs
@@ -177,6 +177,7 @@ pub enum ControlMessageContent {
 #[derive(Copy, Clone, Debug)]
 pub struct ControlMessageClosePort {
     pub closed_in_sync_round: bool, // needed to ensure correct handling of errors
+    pub registered_round: Option<u32>,
 }
 
 // -----------------------------------------------------------------------------
diff --git a/src/runtime2/component/component.rs b/src/runtime2/component/component.rs
index 67dd569364fdf0803e7cbd6e13012cdac1b22975..d62e12376dc8a3aad288ca6dd4688da39fd99750 100644
--- a/src/runtime2/component/component.rs
+++ b/src/runtime2/component/component.rs
@@ -278,6 +278,7 @@ pub(crate) fn default_send_data_message(
     let port_handle = comp_ctx.get_port_handle(transmitting_port_id);
     let port_info = comp_ctx.get_port_mut(port_handle);
     port_info.last_instruction = port_instruction;
+    port_info.last_registered_round = Some(consensus.round_number());
 
     let port_info = comp_ctx.get_port(port_handle);
     debug_assert_eq!(port_info.kind, PortKind::Putter);
@@ -511,9 +512,10 @@ pub(crate) fn default_handle_received_data_message(
     }
 
     // Modify last-known location where port instruction was retrieved
-    let port_info = comp_ctx.get_port(port_handle);
+    let port_info = comp_ctx.get_port_mut(port_handle);
     debug_assert_ne!(port_info.last_instruction, PortInstruction::None); // set by caller
     debug_assert!(port_info.state.is_open()); // checked by caller
+    port_info.last_registered_round = Some(message.sync_header.sync_round);
 
     // Check if there are any more messages in the backup buffer
     for message_index in 0..inbox_backup.len() {
@@ -591,6 +593,7 @@ pub(crate) fn default_handle_control_message(
             } else {
                 // Respond to the message
                 let port_info = comp_ctx.get_port(port_handle);
+                let last_registered_round = port_info.last_registered_round;
                 let last_instruction = port_info.last_instruction;
                 let port_has_had_message = port_info.received_message_for_sync;
                 default_send_ack(message.id, peer_handle, sched_ctx, comp_ctx);
@@ -607,10 +610,11 @@ pub(crate) fn default_handle_control_message(
                 let port_was_used = last_instruction != PortInstruction::None;
 
                 if exec_state.mode.is_in_sync_block() {
-                    let closed_during_sync_round = content.closed_in_sync_round && port_was_used;
-                    let closed_before_sync_round = !content.closed_in_sync_round && !port_has_had_message && port_was_used;
+                    let round_has_succeeded = !content.closed_in_sync_round && last_registered_round == content.registered_round;
+                    let closed_during_sync_round = content.closed_in_sync_round;
+                    let closed_before_sync_round = ! closed_during_sync_round && !round_has_succeeded;
 
-                    if closed_during_sync_round || closed_before_sync_round {
+                    if (closed_during_sync_round || closed_before_sync_round) && port_was_used {
                         return Err((
                             last_instruction,
                             format!("Peer component (id:{}) shut down, so communication cannot (have) succeed(ed)", peer_comp_id.0)
diff --git a/src/runtime2/component/component_context.rs b/src/runtime2/component/component_context.rs
index 1d00c2c83fa9b0ae269fe690f659ef94cf4c9e1d..8bf9189d82ed212972b3acfc4bf5aeecf3352fbe 100644
--- a/src/runtime2/component/component_context.rs
+++ b/src/runtime2/component/component_context.rs
@@ -129,6 +129,7 @@ pub struct Port {
     pub kind: PortKind,
     pub state: PortState,
     // State tracking for error detection and error handling
+    pub last_registered_round: Option<u32>,
     pub last_instruction: PortInstruction, // used during sync round to detect port-closed-during-sync errors
     pub received_message_for_sync: bool, // used during sync round to detect port-closed-before-sync errors
     pub close_at_sync_end: bool, // set during sync round when receiving a port-closed-after-sync message
@@ -181,6 +182,7 @@ impl CompCtx {
             kind: PortKind::Putter,
             state: PortState::new(),
             peer_comp_id: self.id,
+            last_registered_round: None,
             last_instruction: PortInstruction::None,
             close_at_sync_end: false,
             received_message_for_sync: false,
@@ -192,6 +194,7 @@ impl CompCtx {
             kind: PortKind::Getter,
             state: PortState::new(),
             peer_comp_id: self.id,
+            last_registered_round: None,
             last_instruction: PortInstruction::None,
             close_at_sync_end: false,
             received_message_for_sync: false,
@@ -206,6 +209,7 @@ impl CompCtx {
         let self_id = PortId(self.take_port_id());
         self.ports.push(Port{
             self_id, peer_comp_id, peer_port_id, kind, state,
+            last_registered_round: None,
             last_instruction: PortInstruction::None,
             close_at_sync_end: false,
             received_message_for_sync: false,
diff --git a/src/runtime2/component/consensus.rs b/src/runtime2/component/consensus.rs
index e4706c27995c39138d51ef1629058bcca6d0d004..db9a1e3c366b8118a8d58e038ea8d823741002d7 100644
--- a/src/runtime2/component/consensus.rs
+++ b/src/runtime2/component/consensus.rs
@@ -270,6 +270,11 @@ impl Consensus {
         }
     }
 
+    #[inline]
+    pub(crate) fn round_number(&self) -> u32 {
+        return self.round_index;
+    }
+
     // -------------------------------------------------------------------------
     // Managing sync state
     // -------------------------------------------------------------------------
diff --git a/src/runtime2/component/control_layer.rs b/src/runtime2/component/control_layer.rs
index 9eabc0cd5f0534f877c7251c46b1296ac11bfbf4..f3ec7e5150968c3d93f6d187a1ffd1f27689d466 100644
--- a/src/runtime2/component/control_layer.rs
+++ b/src/runtime2/component/control_layer.rs
@@ -264,6 +264,7 @@ impl ControlLayer {
                 target_port_id: Some(peer_port_id),
                 content: ControlMessageContent::ClosePort(ControlMessageClosePort{
                     closed_in_sync_round: exit_inside_sync,
+                    registered_round: port.last_registered_round,
                 }),
             }
         );