Why is there a technical error when trying to add the Express Add-Ons widget? The error message is "bsub-express-add-ons" not added. Liquid templates don’t support sections and blocks.
The Express Add-Ons widget is only compatible with Online Store 2.0 themes. If you are using a vintage theme, you will need to switch to a 2.0 theme in order to use this feature. The error message you are seeing is because Liquid templates do not support sections and blocks, which are required for the widget to function properly. You may be able to make changes to the standard subscription widget from within your theme files to address the language styling and CSS styling.