diff --git a/src/main/java/org/opentripplanner/model/plan/legreference/LegReferenceSerializer.java b/src/main/java/org/opentripplanner/model/plan/legreference/LegReferenceSerializer.java
index 4f090a440b6..c5c38fd2506 100644
--- a/src/main/java/org/opentripplanner/model/plan/legreference/LegReferenceSerializer.java
+++ b/src/main/java/org/opentripplanner/model/plan/legreference/LegReferenceSerializer.java
@@ -51,8 +51,14 @@ public static LegReference decode(String legReference) {
       return null;
     }
 
-    var buf = Base64.getUrlDecoder().decode(legReference);
-    var input = new ByteArrayInputStream(buf);
+    byte[] serializedLegReference;
+    try {
+      serializedLegReference = Base64.getUrlDecoder().decode(legReference);
+    } catch (IllegalArgumentException e) {
+      LOG.info("Unable to decode leg reference (invalid base64 encoding): '{}'", legReference, e);
+      return null;
+    }
+    var input = new ByteArrayInputStream(serializedLegReference);
 
     try (var in = new ObjectInputStream(input)) {
       // The order must be the same in the encode and decode function
@@ -60,7 +66,11 @@ public static LegReference decode(String legReference) {
       var type = readEnum(in, LegReferenceType.class);
       return type.getDeserializer().read(in);
     } catch (IOException e) {
-      LOG.error("Unable to decode leg reference: '" + legReference + "'", e);
+      LOG.info(
+        "Unable to decode leg reference (incompatible serialization format): '{}'",
+        legReference,
+        e
+      );
       return null;
     }
   }
diff --git a/src/test/java/org/opentripplanner/model/plan/legreference/LegReferenceSerializerTest.java b/src/test/java/org/opentripplanner/model/plan/legreference/LegReferenceSerializerTest.java
index da295073e01..2d7df788ad3 100644
--- a/src/test/java/org/opentripplanner/model/plan/legreference/LegReferenceSerializerTest.java
+++ b/src/test/java/org/opentripplanner/model/plan/legreference/LegReferenceSerializerTest.java
@@ -2,6 +2,7 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
 
 import java.time.LocalDate;
 import org.junit.jupiter.api.Test;
@@ -86,4 +87,19 @@ void testScheduledTransitLegReferenceLegacyV2Deserialize() {
     assertEquals(FROM_STOP_POS, ref.fromStopPositionInPattern());
     assertEquals(TO_STOP_POS, ref.toStopPositionInPattern());
   }
+
+  @Test
+  void testNullSerializedLegReference() {
+    assertNull(LegReferenceSerializer.decode(null));
+  }
+
+  @Test
+  void testEmptySerializedLegReference() {
+    assertNull(LegReferenceSerializer.decode(""));
+  }
+
+  @Test
+  void testIllegalBase64CharacterInSerializedLegReference() {
+    assertNull(LegReferenceSerializer.decode("RUT:Line:5"));
+  }
 }