I see an update notification in the console after the upgrade.

Maybe it’s a bug. File old-post-promoter.php and OldPostPromoter.php two similar files with different versions. I see an update notification in the console after the upgrade. I delete old file OldPostPromoter.php and now activate plugin.

<?php
/*
Plugin Name: Old Post Promoter (by BTE)
Plugin URI: http://www.blogtrafficexchange.com/old-post-promoter
Version: 1.9.3

and

<?php

/*

Plugin Name: Old Post Promoter - OPP

Plugin URI: http://www.blogtrafficexchange.com/old-post-promoter/

Author: Blog Traffic Exchange

Author URI: http://www.blogtrafficexchange.com

Version: 3.0.0