diff --git a/php/src/ContainerDefinitionFetcher.php b/php/src/ContainerDefinitionFetcher.php
index 60e92305..7ec5a47a 100644
--- a/php/src/ContainerDefinitionFetcher.php
+++ b/php/src/ContainerDefinitionFetcher.php
@@ -27,7 +27,7 @@ class ContainerDefinitionFetcher
         $this->container = $container;
     }
 
-    public function GetContainerById(string $id): ?Container
+    public function GetContainerById(string $id): Container
     {
         $containers = $this->FetchDefinition();
 
@@ -36,8 +36,7 @@ class ContainerDefinitionFetcher
                 return $container;
             }
         }
-
-        return null;
+        throw new Exception("The provided id " . $id . " was not found in the container definition.");
     }
 
     /**