wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php:126Checks if a given request has access to create an attachment.
$requestWP_REST_Requesttrue|WP_ErrorOne hook fires while WP_REST_Attachments_Controller::create_item_permissions_check() runs, in this order:
Filter whether the server should prevent uploads for image types it doesn't support. Default true.
public function create_item_permissions_check( $request ) { $ret = parent::create_item_permissions_check( $request ); if ( ! $ret || is_wp_error( $ret ) ) { return $ret; } if ( ! current_user_can( 'upload_files' ) ) { return new WP_Error( 'rest_cannot_create', __( 'Sorry, you are not allowed to upload media on this site.' ), array( 'status' => 400 ) ); } // Attaching media to a post requires ability to edit said post. if ( ! empty( $request['post'] ) && ! current_user_can( 'edit_post', (int) $request['post'] ) ) { return new WP_Error( 'rest_cannot_edit', __( 'Sorry, you are not allowed to upload media to this post.' ), array( 'status' => rest_authorization_required_code() ) ); } $files = $request->get_file_params(); /** * Filter whether the server should prevent uploads for image types it doesn't support. Default true. * * Developers can use this filter to enable uploads of certain image types. By default image types that are not * supported by the server are prevented from being uploaded. * * @since 6.8.0 * * @param bool $check_mime Whether to prevent uploads of unsupported image types. * @param string|null $mime_type The mime type of the file being uploaded (if available). */ $prevent_unsupported_uploads = apply_filters( 'wp_prevent_unsupported_mime_type_uploads', true, $files['file']['type'] ?? null ); // If the upload is an image, check if the server can handle the mime type. if ( $prevent_unsupported_uploads && isset( $files['file']['type'] ) && str_starts_with( $files['file']['type'], 'image/' ) ) { // List of non-resizable image formats. $editor_non_resizable_formats = array( 'image/svg+xml', ); // Check if the image editor supports the type or ignore if it isn't a format resizable by an editor. if ( ! in_array( $files['file']['type'], $editor_non_resizable_formats, true ) && ! wp_image_editor_supports( array( 'mime_type' => $files['file']['type'] ) ) ) { return new WP_Error( 'rest_upload_image_type_not_supported', __( 'The web server cannot generate responsive image sizes for this image. Convert it to JPEG or PNG before uploading.' ), array( 'status' => 400 ) ); } } return true; }Introduced in 4.7.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.