diff --git a/src/convert_to_python.py b/src/convert_to_python.py
index e1e1aa2b..a8685f48 100644
--- a/src/convert_to_python.py
+++ b/src/convert_to_python.py
@@ -168,10 +168,24 @@ def make_edge_data(data: dict) -> list[dict]:
                         f"Invalid source handle '{edge['sourceHandle']}' for {edge}."
                     )
             else:
+                # make sure that the source block has only one output port (ie. that sourceHandle is None)
+                assert edge["sourceHandle"] is None, (
+                    f"Source block {block.id} has multiple output ports, "
+                    "but connection method hasn't been implemented."
+                )
                 output_index = 0
 
             if isinstance(target_block, Scope):
                 input_index = target_block._connections_order.index(edge["id"])
+            elif isinstance(target_block, Bubbler):
+                if edge["targetHandle"] == "sample_in_soluble":
+                    input_index = 0
+                elif edge["targetHandle"] == "sample_in_insoluble":
+                    input_index = 1
+                else:
+                    raise ValueError(
+                        f"Invalid target handle '{edge['targetHandle']}' for {edge}."
+                    )
             elif isinstance(target_block, FestimWall):
                 if edge["targetHandle"] == "c_0":
                     input_index = 0
@@ -182,6 +196,11 @@ def make_edge_data(data: dict) -> list[dict]:
                         f"Invalid target handle '{edge['targetHandle']}' for {edge}."
                     )
             else:
+                # make sure that the target block has only one input port (ie. that targetHandle is None)
+                assert edge["targetHandle"] is None, (
+                    f"Target block {target_block.id} has multiple input ports, "
+                    "but connection method hasn't been implemented."
+                )
                 input_index = block_to_input_index[target_block]
 
             edge["source_var_name"] = node["var_name"]
diff --git a/src/pathsim_utils.py b/src/pathsim_utils.py
index 0274f377..c1554525 100644
--- a/src/pathsim_utils.py
+++ b/src/pathsim_utils.py
@@ -437,11 +437,24 @@ def make_connections(nodes, edges, blocks) -> list[Connection]:
                         f"Invalid source handle '{edge['sourceHandle']}' for {edge}."
                     )
             else:
+                # make sure that the source block has only one output port (ie. that sourceHandle is None)
+                assert edge["sourceHandle"] is None, (
+                    f"Source block {block.id} has multiple output ports, "
+                    "but connection method hasn't been implemented."
+                )
                 output_index = 0
 
             if isinstance(target_block, Scope):
                 input_index = target_block._connections_order.index(edge["id"])
-            # TODO we should do the same for all blocks with several input/target ports
+            elif isinstance(target_block, Bubbler):
+                if edge["targetHandle"] == "sample_in_soluble":
+                    input_index = 0
+                elif edge["targetHandle"] == "sample_in_insoluble":
+                    input_index = 1
+                else:
+                    raise ValueError(
+                        f"Invalid target handle '{edge['targetHandle']}' for {edge}."
+                    )
             elif isinstance(target_block, FestimWall):
                 if edge["targetHandle"] == "c_0":
                     input_index = 0
@@ -452,6 +465,11 @@ def make_connections(nodes, edges, blocks) -> list[Connection]:
                         f"Invalid target handle '{edge['targetHandle']}' for {edge}."
                     )
             else:
+                # make sure that the target block has only one input port (ie. that targetHandle is None)
+                assert edge["targetHandle"] is None, (
+                    f"Target block {target_block.id} has multiple input ports, "
+                    "but connection method hasn't been implemented."
+                )
                 input_index = block_to_input_index[target_block]
 
             connection = Connection(
diff --git a/test/test_convert_python.py b/test/test_convert_python.py
index d70660e7..38dfc6ea 100644
--- a/test/test_convert_python.py
+++ b/test/test_convert_python.py
@@ -41,11 +41,41 @@
         },
     ],
     "edges": [
-        {"source": "1", "target": "2", "id": "e1-2"},
-        {"source": "2", "target": "3", "id": "e2-3"},
-        {"source": "3", "target": "4", "id": "e3-4"},
-        {"source": "3", "target": "5", "id": "e3-5"},
-        {"source": "4", "target": "5", "id": "e4-5"},
+        {
+            "source": "1",
+            "target": "2",
+            "id": "e1-2",
+            "sourceHandle": None,
+            "targetHandle": None,
+        },
+        {
+            "source": "2",
+            "target": "3",
+            "id": "e2-3",
+            "sourceHandle": None,
+            "targetHandle": None,
+        },
+        {
+            "source": "3",
+            "target": "4",
+            "id": "e3-4",
+            "sourceHandle": None,
+            "targetHandle": None,
+        },
+        {
+            "source": "3",
+            "target": "5",
+            "id": "e3-5",
+            "sourceHandle": None,
+            "targetHandle": None,
+        },
+        {
+            "source": "4",
+            "target": "5",
+            "id": "e4-5",
+            "sourceHandle": None,
+            "targetHandle": None,
+        },
     ],
     "solverParams": {
         "Solver": "SSPRK22",