diff --git a/src/API/CourseProviderInterface.php b/src/API/CourseProviderInterface.php
index ee946fcdae79860435ec901b9be3b7a7597205ab..b08634d29ffc278719c98017cc38399b3282a4ae 100644
--- a/src/API/CourseProviderInterface.php
+++ b/src/API/CourseProviderInterface.php
@@ -6,28 +6,40 @@ namespace Dbp\Relay\BaseCourseBundle\API;
 
 use Dbp\Relay\BaseCourseBundle\Entity\Course;
 use Dbp\Relay\BaseCourseBundle\Entity\CourseAttendee;
+use Dbp\Relay\CoreBundle\Exception\ApiError;
 
 interface CourseProviderInterface
 {
-    public function getCourseById(string $identifier, array $options = []): ?Course;
+    /**
+     * @throws ApiError
+     */
+    public function getCourseById(string $identifier, array $options = []): Course;
 
     /**
      * @return Course[]
+     *
+     * @throws ApiError
      */
     public function getCourses(array $options = []): array;
 
     /**
      * @return Course[]
+     *
+     * @throws ApiError
      */
     public function getCoursesByOrganization(string $orgUnitId, array $options = []): array;
 
     /**
      * @return Course[]
+     *
+     * @throws ApiError
      */
     public function getCoursesByLecturer(string $lecturerId, array $options = []): array;
 
     /**
      * @return CourseAttendee[]
+     *
+     * @throws ApiError
      */
     public function getAttendeesByCourse(string $courseId, array $options = []): array;
 }
diff --git a/src/Service/DummyCourseProvider.php b/src/Service/DummyCourseProvider.php
index f5683fe05622b96c13e39bc74dc592df5ea9fab9..2de0a9dad1661ec1c794be3a5d3f982a04045926 100644
--- a/src/Service/DummyCourseProvider.php
+++ b/src/Service/DummyCourseProvider.php
@@ -10,7 +10,7 @@ use Dbp\Relay\BaseCourseBundle\Entity\CourseAttendee;
 
 class DummyCourseProvider implements CourseProviderInterface
 {
-    public function getCourseById(string $identifier, array $options = []): ?Course
+    public function getCourseById(string $identifier, array $options = []): Course
     {
         $course = new Course();
         $course->setIdentifier($identifier);