diff --git a/app/V1Module/presenters/ExerciseFilesPresenter.php b/app/V1Module/presenters/ExerciseFilesPresenter.php
index 85b7611fc..f1f67c37a 100644
--- a/app/V1Module/presenters/ExerciseFilesPresenter.php
+++ b/app/V1Module/presenters/ExerciseFilesPresenter.php
@@ -7,6 +7,7 @@
 use App\Helpers\MetaFormats\Validators\VMixed;
 use App\Helpers\MetaFormats\Validators\VString;
 use App\Helpers\MetaFormats\Validators\VUuid;
+use App\Exceptions\BadRequestException;
 use App\Exceptions\ForbiddenRequestException;
 use App\Exceptions\InvalidApiArgumentException;
 use App\Exceptions\NotFoundException;
@@ -17,6 +18,7 @@
 use App\Model\Entity\SupplementaryExerciseFile;
 use App\Model\Entity\UploadedFile;
 use App\Model\Entity\AttachmentFile;
+use App\Model\Repository\Assignments;
 use App\Model\Repository\AttachmentFiles;
 use App\Model\Repository\Exercises;
 use App\Model\Entity\Exercise;
@@ -37,6 +39,12 @@ class ExerciseFilesPresenter extends BasePresenter
      */
     public $exercises;
 
+    /**
+     * @var Assignments
+     * @inject
+     */
+    public $assignments;
+
     /**
      * @var UploadedFiles
      * @inject
@@ -323,6 +331,10 @@ public function actionGetAttachmentFiles(string $id)
     public function checkDeleteAttachmentFile(string $id, string $fileId)
     {
         $exercise = $this->exercises->findOrThrow($id);
+        $file = $this->attachmentFiles->findOrThrow($fileId);
+        if (!$file->getExercises()->contains($exercise)) {
+            throw new BadRequestException("Selected file is not an attachment file for given exercise.");
+        }
         if (!$this->exerciseAcl->canUpdate($exercise)) {
             throw new ForbiddenRequestException("You cannot delete attachment files for this exercise.");
         }
@@ -345,7 +357,37 @@ public function actionDeleteAttachmentFile(string $id, string $fileId)
         $exercise->removeAttachmentFile($file);
         $this->exercises->flush();
 
-        $this->fileStorage->deleteAttachmentFile($file);
+        $this->attachmentFiles->refresh($file);
+        if ($file->getExercises()->isEmpty()) {
+            // file has no attachments to exercises, let's check the assignments
+            $isUsed = false;
+            foreach ($file->getAssignments() as $assignment) {
+                $group = $assignment->getGroup();
+                if ($group && !$group->isArchived()) {
+                    $isUsed = true;  // only non-archived assignments are considered relevant
+                    break;
+                }
+            }
+
+            if (!$isUsed) {
+                $this->fileStorage->deleteAttachmentFile($file);
+
+                if ($file->getAssignments()->isEmpty()) {
+                    // only if no attachments exists (except for deleted ones)
+                    // remove all links to deleted entities and remove the file record
+                    foreach ($file->getExercisesAndIReallyMeanAllOkay() as $exercise) {
+                        $exercise->removeAttachmentFile($file);
+                        $this->exercises->persist($exercise, false);
+                    }
+                    foreach ($file->getAssignmentsAndIReallyMeanAllOkay() as $assignment) {
+                        $assignment->removeAttachmentFile($file);
+                        $this->assignments->persist($assignment, false);
+                    }
+
+                    $this->attachmentFiles->remove($file);
+                }
+            }
+        }
 
         $this->sendSuccessResponse("OK");
     }
diff --git a/app/model/entity/AttachmentFile.php b/app/model/entity/AttachmentFile.php
index a4d6252e8..05be5348a 100644
--- a/app/model/entity/AttachmentFile.php
+++ b/app/model/entity/AttachmentFile.php
@@ -32,6 +32,14 @@ function (Exercise $exercise) {
         );
     }
 
+    /**
+     * @return Collection
+     */
+    public function getExercisesAndIReallyMeanAllOkay()
+    {
+        return $this->exercises;
+    }
+
     /**
      * @ORM\ManyToMany(targetEntity="Assignment", mappedBy="attachmentFiles")
      */
@@ -49,6 +57,13 @@ function (Assignment $assignment) {
         );
     }
 
+    /**
+     * @return Collection
+     */
+    public function getAssignmentsAndIReallyMeanAllOkay()
+    {
+        return $this->assignments;
+    }
 
     /**
      * AttachmentFile constructor.