diff --git a/src/Server.php b/src/Server.php
index 7c4202f9e..f1643336b 100644
--- a/src/Server.php
+++ b/src/Server.php
@@ -1097,6 +1097,7 @@ class Server{
 
 				$generatorClass = $getGenerator($generatorName, $generatorOptions, $name);
 				if($generatorClass === null){
+					$anyWorldFailedToLoad = true;
 					continue;
 				}
 				$creationOptions->setGeneratorClass($generatorClass);
@@ -1133,16 +1134,19 @@ class Server{
 				$generatorName = $this->configGroup->getConfigString("level-type");
 				$generatorOptions = $this->configGroup->getConfigString("generator-settings");
 				$generatorClass = $getGenerator($generatorName, $generatorOptions, $default);
-				if($generatorClass !== null){
-					$creationOptions = WorldCreationOptions::create()
-						->setGeneratorClass($generatorClass)
-						->setGeneratorOptions($generatorOptions);
-					$convertedSeed = Generator::convertSeed($this->configGroup->getConfigString("level-seed"));
-					if($convertedSeed !== null){
-						$creationOptions->setSeed($convertedSeed);
-					}
-					$this->worldManager->generateWorld($default, $creationOptions);
+
+				if($generatorClass === null){
+					$this->getLogger()->emergency($this->getLanguage()->translate(KnownTranslationFactory::pocketmine_level_defaultError()));
+					return false;
 				}
+				$creationOptions = WorldCreationOptions::create()
+					->setGeneratorClass($generatorClass)
+					->setGeneratorOptions($generatorOptions);
+				$convertedSeed = Generator::convertSeed($this->configGroup->getConfigString("level-seed"));
+				if($convertedSeed !== null){
+					$creationOptions->setSeed($convertedSeed);
+				}
+				$this->worldManager->generateWorld($default, $creationOptions);
 			}
 
 			$world = $this->worldManager->getWorldByName($default);