diff --git a/wp-admin/upload.php b/wp-admin/upload.php
index 0a8aa6526b8f..52f5be8b4b1f 100644
--- a/wp-admin/upload.php
+++ b/wp-admin/upload.php
@@ -15,73 +15,99 @@
 
 $message = '';
 if ( ! empty( $_GET['posted'] ) ) {
-	$message                = __( 'Media file updated.' );
+	$message = __( 'Media file updated.' );
+
 	$_SERVER['REQUEST_URI'] = remove_query_arg( array( 'posted' ), $_SERVER['REQUEST_URI'] );
 	unset( $_GET['posted'] );
 }
 
 if ( ! empty( $_GET['attached'] ) && absint( $_GET['attached'] ) ) {
 	$attached = absint( $_GET['attached'] );
+
 	if ( 1 === $attached ) {
 		$message = __( 'Media file attached.' );
 	} else {
-		/* translators: %s: Number of media files. */
-		$message = _n( '%s media file attached.', '%s media files attached.', $attached );
+		$message = sprintf(
+			/* translators: %s: Number of media files. */
+			_n( '%s media file attached.', '%s media files attached.', $attached ),
+			number_format_i18n( $attached )
+		);
 	}
-	$message                = sprintf( $message, $attached );
+
 	$_SERVER['REQUEST_URI'] = remove_query_arg( array( 'detach', 'attached' ), $_SERVER['REQUEST_URI'] );
 	unset( $_GET['detach'], $_GET['attached'] );
 }
 
 if ( ! empty( $_GET['detach'] ) && absint( $_GET['detach'] ) ) {
 	$detached = absint( $_GET['detach'] );
+
 	if ( 1 === $detached ) {
 		$message = __( 'Media file detached.' );
 	} else {
-		/* translators: %s: Number of media files. */
-		$message = _n( '%s media file detached.', '%s media files detached.', $detached );
+		$message = sprintf(
+			/* translators: %s: Number of media files. */
+			_n( '%s media file detached.', '%s media files detached.', $detached ),
+			number_format_i18n( $detached )
+		);
 	}
-	$message                = sprintf( $message, $detached );
+
 	$_SERVER['REQUEST_URI'] = remove_query_arg( array( 'detach', 'attached' ), $_SERVER['REQUEST_URI'] );
 	unset( $_GET['detach'], $_GET['attached'] );
 }
 
 if ( ! empty( $_GET['deleted'] ) && absint( $_GET['deleted'] ) ) {
 	$deleted = absint( $_GET['deleted'] );
+
 	if ( 1 === $deleted ) {
 		$message = __( 'Media file permanently deleted.' );
 	} else {
-		/* translators: %s: Number of media files. */
-		$message = _n( '%s media file permanently deleted.', '%s media files permanently deleted.', $deleted );
+		$message = sprintf(
+			/* translators: %s: Number of media files. */
+			_n( '%s media file permanently deleted.', '%s media files permanently deleted.', $deleted ),
+			number_format_i18n( $deleted )
+		);
 	}
-	$message                = sprintf( $message, $deleted );
+
 	$_SERVER['REQUEST_URI'] = remove_query_arg( array( 'deleted' ), $_SERVER['REQUEST_URI'] );
 	unset( $_GET['deleted'] );
 }
 
 if ( ! empty( $_GET['trashed'] ) && absint( $_GET['trashed'] ) ) {
 	$trashed = absint( $_GET['trashed'] );
+
 	if ( 1 === $trashed ) {
 		$message = __( 'Media file moved to the Trash.' );
 	} else {
-		/* translators: %s: Number of media files. */
-		$message = _n( '%s media file moved to the Trash.', '%s media files moved to the Trash.', $trashed );
+		$message = sprintf(
+			/* translators: %s: Number of media files. */
+			_n( '%s media file moved to the Trash.', '%s media files moved to the Trash.', $trashed ),
+			number_format_i18n( $trashed )
+		);
 	}
-	$message                = sprintf( $message, $trashed );
-	$message               .= ' <a href="' . esc_url( wp_nonce_url( 'upload.php?doaction=undo&action=untrash&ids=' . ( isset( $_GET['ids'] ) ? $_GET['ids'] : '' ), 'bulk-media' ) ) . '">' . __( 'Undo' ) . '</a>';
+
+	$message .= sprintf(
+		' <a href="%1$s">%2$s</a>',
+		esc_url( wp_nonce_url( 'upload.php?doaction=undo&action=untrash&ids=' . ( isset( $_GET['ids'] ) ? $_GET['ids'] : '' ), 'bulk-media' ) ),
+		__( 'Undo' )
+	);
+
 	$_SERVER['REQUEST_URI'] = remove_query_arg( array( 'trashed' ), $_SERVER['REQUEST_URI'] );
 	unset( $_GET['trashed'] );
 }
 
 if ( ! empty( $_GET['untrashed'] ) && absint( $_GET['untrashed'] ) ) {
 	$untrashed = absint( $_GET['untrashed'] );
+
 	if ( 1 === $untrashed ) {
 		$message = __( 'Media file restored from the Trash.' );
 	} else {
-		/* translators: %s: Number of media files. */
-		$message = _n( '%s media file restored from the Trash.', '%s media files restored from the Trash.', $untrashed );
+		$message = sprintf(
+			/* translators: %s: Number of media files. */
+			_n( '%s media file restored from the Trash.', '%s media files restored from the Trash.', $untrashed ),
+			number_format_i18n( $untrashed )
+		);
 	}
-	$message                = sprintf( $message, $untrashed );
+
 	$_SERVER['REQUEST_URI'] = remove_query_arg( array( 'untrashed' ), $_SERVER['REQUEST_URI'] );
 	unset( $_GET['untrashed'] );
 }
@@ -89,11 +115,16 @@
 $messages[1] = __( 'Media file updated.' );
 $messages[2] = __( 'Media file permanently deleted.' );
 $messages[3] = __( 'Error saving media file.' );
-$messages[4] = __( 'Media file moved to the Trash.' ) . ' <a href="' . esc_url( wp_nonce_url( 'upload.php?doaction=undo&action=untrash&ids=' . ( isset( $_GET['ids'] ) ? $_GET['ids'] : '' ), 'bulk-media' ) ) . '">' . __( 'Undo' ) . '</a>';
+$messages[4] = __( 'Media file moved to the Trash.' ) . sprintf(
+	' <a href="%1$s">%2$s</a>',
+	esc_url( wp_nonce_url( 'upload.php?doaction=undo&action=untrash&ids=' . ( isset( $_GET['ids'] ) ? $_GET['ids'] : '' ), 'bulk-media' ) ),
+	__( 'Undo' )
+);
 $messages[5] = __( 'Media file restored from the Trash.' );
 
 if ( ! empty( $_GET['message'] ) && isset( $messages[ $_GET['message'] ] ) ) {
-	$message                = $messages[ $_GET['message'] ];
+	$message = $messages[ $_GET['message'] ];
+
 	$_SERVER['REQUEST_URI'] = remove_query_arg( array( 'message' ), $_SERVER['REQUEST_URI'] );
 }
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 7edb535b150d..8a83feb6c1a7 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-alpha-55630';
+$wp_version = '6.3-alpha-55631';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.