Hop-spider

When dry-hopping a beer you add loose particles to the wort. All these particles need to be removed from the wort (through the trub-container) before tapping. If you tap a beer with particles still floating in it, the tap line can get clogged, preventing you from serving your beer. Check this article.

You might try to prevent this issue by using a hop-spider when the system request hop addition during fermentation. Please do not forget to sanitize the hop-spider.