diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
index 471b8c7122d6..d3e211aabbe6 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
@@ -1459,7 +1459,7 @@ public CodegenModel fromModel(String name, Schema schema, Map<String, Schema> al
             }
             // parent model
             final String parentName = getParentName(composed, allDefinitions);
-            final Schema parent = StringUtils.isBlank(parentName) ? null : allDefinitions.get(parentName);
+            final Schema parent = StringUtils.isBlank(parentName) || allDefinitions == null ? null : allDefinitions.get(parentName);
 
             List<Schema> interfaces = getInterfaces(composed);
 
@@ -4097,7 +4097,12 @@ public List<CodegenParameter> fromRequestBodyToFormParameters(RequestBody body,
                     codegenParameter.isListContainer = true;
                     codegenParameter.description = s.getDescription();
                     codegenParameter.dataType = getTypeDeclaration(s);
-                    codegenParameter.datatypeWithEnum = codegenParameter.dataType.replace(codegenParameter.baseType, codegenParameter.enumName);
+                    if (codegenParameter.baseType != null && codegenParameter.enumName != null){
+                        codegenParameter.datatypeWithEnum = codegenParameter.dataType.replace(codegenParameter.baseType, codegenParameter.enumName);
+                    }
+                    else {
+                        LOGGER.warn("Could not compute datatypeWithEnum from " + codegenParameter.baseType + ", " + codegenParameter.enumName);
+                    }
                     //TODO fix collectformat for form parameters
                     //collectionFormat = getCollectionFormat(s);
                     // default to csv: