diff --git a/llama_stack/core/store/registry.py b/llama_stack/core/store/registry.py
index 5f4abe9aa..5491ab0f1 100644
--- a/llama_stack/core/store/registry.py
+++ b/llama_stack/core/store/registry.py
@@ -98,7 +98,10 @@ class DiskDistributionRegistry(DistributionRegistry):
         existing_obj = await self.get(obj.type, obj.identifier)
         # dont register if the object's providerid already exists
         if existing_obj and existing_obj.provider_id == obj.provider_id:
-            return False
+            raise ValueError(
+                f"Model '{obj.identifier}' is already registered with provider '{obj.provider_id}'. "
+                f"Please unregister the existing model first before registering a new one."
+            )
 
         await self.kvstore.set(
             KEY_FORMAT.format(type=obj.type, identifier=obj.identifier),
diff --git a/tests/unit/registry/test_registry.py b/tests/unit/registry/test_registry.py
index 4ea4a20b9..5d8add4bf 100644
--- a/tests/unit/registry/test_registry.py
+++ b/tests/unit/registry/test_registry.py
@@ -125,8 +125,12 @@ async def test_duplicate_provider_registration(cached_disk_dist_registry):
         provider_resource_id="test_vector_db_2",
         provider_id="baz",  # Same provider_id
     )
-    await cached_disk_dist_registry.register(duplicate_vector_db)
 
+    # Now we expect a ValueError to be raised for duplicate registration
+    with pytest.raises(ValueError, match=r".*already registered.*"):
+        await cached_disk_dist_registry.register(duplicate_vector_db)
+
+    # Verify the original registration is still intact
     result = await cached_disk_dist_registry.get("vector_db", "test_vector_db_2")
     assert result is not None
     assert result.embedding_model == original_vector_db.embedding_model  # Original values preserved