Quote Originally Posted by archelaus View Post
OPC 2.0.5 and ZC 1.5.6a. I hate to waste people's time with something I should be able to figure out by myself, but I'm stumped. In guest checkout, the customer's billing address is pre-filling with the state/province listed for the store in Configuration>My Store and the zip code listed for the store in Configuration>Shipping/Packaging. I'm okay with it defaulting to USA, but I'd like state and zip code to be blank. I'm not seeing anything in Configuration>One-Page Checkout Settings, and the code in tpl_modules_opc_address_block.php is over my head. Thanks in advance!
That pre-filling of country/state/postcode was introduced in OPC 2.0.1 to address the issue where some shipping modules (like USPS) don't send back quotes and, to my remembrance, also throw debug-logs if those fields aren't present in the 'order-object' when the shipping-modules are loaded. See this (https://github.com/lat9/one_page_checkout/issues/133) issue for additional information.

If it's important for you to not pre-fill those fields, you could make store-specific changes to the OnePageCheckout.php class-file, backing out the changes provided in the issue referenced above. Just remember, if you choose to, that you'll need to merge those changes into that class-file whenever you update your version of OPC.