Use with caution: When you use the upgrader_process_complete action hook in your plugin and your plugin is the one which under upgrade, then this action will run the old version of your plugin.

This was found in the Wordpress documentation.

I’ve tested it and it in fact runs from the old version of the plugin, not the updated one, which makes it fairy useless if you want to for example change table structure of your custom DB tables in the new version.

Hi – that’s a good question. I believe it runs from the updated version but I haven’t checked this.

I have one question about this hook: when it triggers, the updated plugin is already running on the updated version right? or when this triggers the plugin still is on the older version?