from https://github.com/ArneBinder/pie-document-level/pull/301

app.py

@@ -502,7 +502,7 @@ def main():
                     with gr.Row():
                         download_processed_documents_btn = gr.DownloadButton("Download")
                         upload_processed_documents_btn = gr.UploadButton(
-                            "Upload", file_types=["files"]
+                            "Upload", file_types=["file"]
                         )
 
                 upload_btn = gr.UploadButton(