Why do my customers get "Your checkout information has changed. Please review your shipping options and try again" at checkout?
The HTML templates that control your checkout pages contain validation scripts intended to prevent fraudulent order activity. They are an important component of your store's structure and security. However, as technologies change and evolve, these script tend to be updated often.
Your Shift4Shop store's common folder houses all of the most up to date HTML templates needed by the system. However, if you have made HTML customizations to your checkout page templates, then those pages are no longer coming from the common folder and therefore may not have the latest updates to validation scripts.
In cases like these you may see the error listed above (or similar checkout validation errors) quite frequently instead of under very specific and rare circumstances as intended.
As stated, the common folder contains all of the most up to date versions of HTML templates your store needs. When you make customizations to the store's HTML templates, those files are no longer being served from the common folder. Instead, they are served from your Theme folder. So any updates made to the scripting and coding of the page may not be present on your store and you'll see issues more commonly like the error message mentioned above.
The fastest way to correct this is to simply remove (or alter the name of your customized template) so that the file is served from the common folder.
The following article will give you details on how to perform this process: