By default, OpenCart shows a generic message like “Select required!” when a customer tries to add a product to the cart without choosing a required option.
This extension lets you replace that default text with your own custom message, defined individually for each option.
For example, instead of the vague “Select required!”, you can display messages such as:

“Please choose your size before adding to cart.”
“Select a color to continue.”
“Pick a delivery date before proceeding.”

Features

Adds a new “Alert message” field in the option editor in the admin panel.
Supports multiple languages — each alert can be translated separately.
Works automatically on the product page without changing template files.
Uses OpenCart’s built-in OCMod system — no core files are modified.