diff --git a/electrum/lnpeer.py b/electrum/lnpeer.py
index a8a60382b..35bf33754 100644
--- a/electrum/lnpeer.py
+++ b/electrum/lnpeer.py
@@ -2801,8 +2801,8 @@ class Peer(Logger, EventListener):
                                 self.lnworker.active_forwardings[payment_key].append(next_htlc)
                                 self.lnworker.downstream_to_upstream_htlc[next_htlc] = htlc_key
                         except OnionRoutingFailure as e:
-                            assert len(self.lnworker.active_forwardings[payment_key]) == 0
-                            self.lnworker.save_forwarding_failure(payment_key, failure_message=e)
+                            if len(self.lnworker.active_forwardings[payment_key]) == 0:
+                                self.lnworker.save_forwarding_failure(payment_key, failure_message=e)
                         # TODO what about other errors? e.g. TxBroadcastError for a swap.
                         #        - malicious electrum server could fake TxBroadcastError
                         #      Could we "catch-all Exception" and fail back the htlcs with e.g. TEMPORARY_NODE_FAILURE?
diff --git a/tests/test_lnpeer.py b/tests/test_lnpeer.py
index 0e51a2740..84bbbb616 100644
--- a/tests/test_lnpeer.py
+++ b/tests/test_lnpeer.py
@@ -1950,7 +1950,8 @@ class TestPeerForwarding(TestPeer):
         graph = self.prepare_chans_and_peers_in_graph(graph_definition)
         if test_mpp_consolidation:
             graph.workers['dave'].features |= LnFeatures.BASIC_MPP_OPT
-            graph.workers['alice'].network.config.TEST_FORCE_MPP = True
+            graph.workers['alice'].network.config.TEST_FORCE_MPP = True # trampoline must wait until all incoming htlcs are received before sending outgoing htlcs
+            graph.workers['bob'].network.config.TEST_FORCE_MPP = True   # trampoline must wait until all outgoing htlcs have failed before failing incoming htlcs
         if is_legacy:
             # turn off trampoline features in invoice
             graph.workers['dave'].features = graph.workers['dave'].features ^ LnFeatures.OPTION_TRAMPOLINE_ROUTING_OPT_ELECTRUM