diff --git a/frontend/src/components/competition/ProjectSubmission.jsx b/frontend/src/components/competition/ProjectSubmission.jsx
index 2a5727f..19e5a0d 100644
--- a/frontend/src/components/competition/ProjectSubmission.jsx
+++ b/frontend/src/components/competition/ProjectSubmission.jsx
@@ -169,10 +169,14 @@ const ProjectSubmission = ({ competitionId, initialValues, onCancel, onSuccess }
     
     const hasFiles = pendingAttachments.length > 0 || pendingCoverImage;
     
-    const data = {
+    let data = {
       ...values,
       competition: competitionId,
     };
+    
+    if (data.cover_image_url && data.cover_image_url.startsWith('data:')) {
+      delete data.cover_image_url;
+    }
 
     if (initialValues?.id) {
       await updateProject(initialValues.id, data);