diff --git a/integrations/openapi/src/parser/spec.test.ts b/integrations/openapi/src/parser/spec.test.ts
index 793621a92..9fa449154 100644
--- a/integrations/openapi/src/parser/spec.test.ts
+++ b/integrations/openapi/src/parser/spec.test.ts
@@ -22,7 +22,7 @@ describe('#divideOpenAPISpecSchema', () => {
     it('respects the tags', async () => {
         const schema = await dereferenceOpenAPISpec(rawSpec);
         // Change the order of tags
-        schema.tags = [{ name: 'store' }, { name: 'pet' }];
+        schema.tags = [{ name: 'store' }, { name: 'pet' }, { name: 'unknown' }];
         const groups = divideOpenAPISpecSchema(schema);
         expect(groups).toHaveLength(2);
         expect(groups[0].id).toBe('store');
diff --git a/integrations/openapi/src/parser/spec.ts b/integrations/openapi/src/parser/spec.ts
index 5a604c654..bd03faedf 100644
--- a/integrations/openapi/src/parser/spec.ts
+++ b/integrations/openapi/src/parser/spec.ts
@@ -133,11 +133,13 @@ export function divideOpenAPISpecSchema(schema: OpenAPIV3.Document): OpenAPIGrou
 
     // If the schema has tags, use this order to sort the groups.
     if (schema.tags) {
-        return schema.tags.map((tag) => {
+        return schema.tags.reduce<OpenAPIGroup[]>((tagGroups, tag) => {
             const group = groups.find((group) => group.id === tag.name);
-            assert(group, `Group not found for tag ${tag.name}`);
-            return group;
-        });
+            if (group) {
+                tagGroups.push(group);
+            }
+            return tagGroups;
+        }, []);
     }
 
     return groups;