diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 87b1c86..ee706e5 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -7013,7 +7013,12 @@
         const QuicSocketAddress& direct_peer_address)
     : QuicPathValidator::ResultDelegate(),
       connection_(connection),
-      original_direct_peer_address_(direct_peer_address) {}
+      original_direct_peer_address_(direct_peer_address),
+      peer_address_default_path_(connection->direct_peer_address_),
+      peer_address_alternative_path_(
+          connection_->alternative_path_.peer_address),
+      active_effective_peer_migration_type_(
+          connection_->active_effective_peer_migration_type_) {}
 
 void QuicConnection::ReversePathValidationResultDelegate::
     OnPathValidationSuccess(
@@ -7022,6 +7027,30 @@
   if (connection_->IsDefaultPath(context->self_address(),
                                  context->peer_address())) {
     QUIC_CODE_COUNT_N(quic_kick_off_client_address_validation, 3, 6);
+    if (connection_->active_effective_peer_migration_type_ == NO_CHANGE) {
+      connection_->quic_bug_10511_43_timestamp_ =
+          connection_->clock_->WallNow();
+      connection_->quic_bug_10511_43_error_detail_ = absl::StrCat(
+          "Reverse path validation on default path from ",
+          context->self_address().ToString(), " to ",
+          context->peer_address().ToString(),
+          " completed without active peer address change: current "
+          "peer address on default path ",
+          connection_->direct_peer_address_.ToString(),
+          ", peer address on default path when the reverse path "
+          "validation was kicked off ",
+          peer_address_default_path_.ToString(),
+          ", peer address on alternative path when the reverse "
+          "path validation was kicked off ",
+          peer_address_alternative_path_.ToString(),
+          ", with active_effective_peer_migration_type_ = ",
+          AddressChangeTypeToString(active_effective_peer_migration_type_),
+          ". The last received packet number ",
+          connection_->last_header_.packet_number.ToString(),
+          " Connection is connected: ", connection_->connected_);
+      QUIC_BUG(quic_bug_10511_43)
+          << connection_->quic_bug_10511_43_error_detail_;
+    }
     connection_->OnEffectivePeerMigrationValidated();
   } else {
     QUICHE_DCHECK(connection_->IsAlternativePath(
diff --git a/quic/core/quic_connection.h b/quic/core/quic_connection.h
index 1ec7c7e..0709a78 100644
--- a/quic/core/quic_connection.h
+++ b/quic/core/quic_connection.h
@@ -1259,6 +1259,14 @@
     context_.tracer.swap(tracer);
   }
 
+  absl::optional<QuicWallTime> quic_bug_10511_43_timestamp() const {
+    return quic_bug_10511_43_timestamp_;
+  }
+
+  const std::string& quic_bug_10511_43_error_detail() const {
+    return quic_bug_10511_43_error_detail_;
+  }
+
  protected:
   // Calls cancel() on all the alarms owned by this connection.
   void CancelAllAlarms();
@@ -1479,6 +1487,11 @@
    private:
     QuicConnection* connection_;
     QuicSocketAddress original_direct_peer_address_;
+    // TODO(b/205023946) Debug-only fields, to be deprecated after the bug is
+    // fixed.
+    QuicSocketAddress peer_address_default_path_;
+    QuicSocketAddress peer_address_alternative_path_;
+    AddressChangeType active_effective_peer_migration_type_;
   };
 
   // A class which sets and clears in_on_retransmission_time_out_ when entering
@@ -2277,6 +2290,11 @@
   const bool reset_per_packet_state_for_undecryptable_packets_ =
       GetQuicReloadableFlag(
           quic_reset_per_packet_state_for_undecryptable_packets);
+
+  // TODO(b/205023946) Debug-only fields, to be deprecated after the bug is
+  // fixed.
+  absl::optional<QuicWallTime> quic_bug_10511_43_timestamp_;
+  std::string quic_bug_10511_43_error_detail_;
 };
 
 }  // namespace quic