diff --git a/test/framework/src/main/java/org/elasticsearch/datageneration/FieldType.java b/test/framework/src/main/java/org/elasticsearch/datageneration/FieldType.java
index 94cd0b05f57df..ec53e3e68d4b2 100644
--- a/test/framework/src/main/java/org/elasticsearch/datageneration/FieldType.java
+++ b/test/framework/src/main/java/org/elasticsearch/datageneration/FieldType.java
@@ -108,7 +108,8 @@ public static FieldType tryParse(String name) {
             case "wildcard" -> FieldType.WILDCARD;
             case "passthrough" -> FieldType.PASSTHROUGH;
             case "match_only_text" -> FieldType.MATCH_ONLY_TEXT;
-            default -> throw new IllegalArgumentException("Unknown field type: " + name);
+            // Custom types will fail to parse and will return null
+            default -> null;
         };
     }