I have use extension https://github.com/EaDesgin/Magento2-City-Dropdown to show city in dropdown but when I enable this extension, city is showing blank in address section of checkout payment page. 
If I tap on "Place order" button then it shows below error:
Please check the billing address information. city is a required field Please check this file in your theme:
Magento_Checkout/web/template/shipping-information/address-renderer/default.html
City Should be remove from there, if yes then please add below code:-
<!-- ko text: address().city --><!-- /ko --> Then File should be look like this:-
<div class="shipping-address-item" data-bind="css: isSelected() ? 'selected-item' : 'not-selected-item'"> <!-- ko text: address().prefix --><!-- /ko --> <!-- ko text: address().firstname --><!-- /ko --> <!-- ko text: address().lastname --><!-- /ko --> <!-- ko text: address().suffix --><!-- /ko --><br/> <!-- ko text: address().street --><!-- /ko --><br/> <!-- ko text: address().city --><!-- /ko -->, <!-- ko text: address().region --><!-- /ko --> <!-- ko text: address().postcode --><!-- /ko --><br/> <!-- ko text: getCountryName(address().countryId) --><!-- /ko --><br/> <!-- ko text: address().telephone --><!-- /ko --><br/> <!-- ko foreach: { data: address().customAttributes, as: 'element' } --> <!-- ko foreach: { data: Object.keys(element), as: 'attribute' } --> <!-- ko text: element[attribute].value --><!-- /ko --> <!-- /ko --> <!-- /ko --> <!-- ko if: (address().isEditable()) --> <button type="button" class="action edit-address-link" data-bind="click: editAddress, visible: address().isEditable()"> <span data-bind="i18n: 'Edit'"></span> </button> <!-- /ko --> <button type="button" data-bind="click: selectAddress" class="action action-select-shipping-item"> <span data-bind="i18n: 'Ship Here'"></span> </button> </div> You need to rewrite and add the following validations to these js files:
magento/vendor/eadesignro/romcity/view/frontend/web/js/action/set-shipping-information-mixin.js:15
if (shippingCityIdValue.length) { shippingAddress.city = shippingCityIdValue; } magento/vendor/eadesignro/romcity/view/frontend/web/js/view/billing-address.js:62
Replace
if (this.isAddressSameAsShipping()) { newAddress.city = shippingCityIdValue; } else if (billingAddressCity) { newAddress.city = billingAddressCity.text(); } else { newAddress.city = shippingCityIdValue; } with:
if (shippingCityIdValue) { newAddress.city = shippingCityIdValue; } if (!this.isAddressSameAsShipping() && billingAddressCity && billingAddressCity.text()) { newAddress.city = billingAddressCity.text(); } It seems that they try to add the city from the form but the values are not present anymore when you already have an address set.
