Mryntu

The data that code references (sectionLoadUrl) is usually set in the following snippet that (should) be on every Magento front-end page

<script type="text/x-magento-init">
"*":"Magento_Customer/js/customer-data":"sectionLoadUrl":"http://magento-2-1-4.dev/customer/section/load/","cookieLifeTime":"3600","updateSessionUrl":"http://magento-2-1-4.dev/customer/account/updateSession/" 
</script>

So, either something in your system removed this snippet, or you're somehow invoking the functionality in Magento_Customer/js/customer-data before the snippet's had a chance to run.

I fixed it by adding following code to <Magento_directry>/app/design/frontend/<Vendor>/<theme>/Magento_Theme/layout/default.xml

 <referenceContainer name="content">
 <block name="customer.section.config" class="MagentoCustomerBlockSectionConfig"
 template="Magento_Customer::js/section-config.phtml"/>
 <block name="customer.customer.data"
 class="MagentoCustomerBlockCustomerData"
 template="Magento_Customer::js/customer-data.phtml"/>
 </referenceContainer>

Check your custom Module model files If you have installed some. There must be some typo error. I have faced the same problem and for me, it works as I have mistaken in Namespace path and due to that typo error it was generating same js error on all pages if not then remove module-customer from pub and try deploy theme again

I solved it removing the default.xml from my theme Magento_Customer.

app/design/frontend/Theme/Name/Magento_Customer/layout/default.xml

I think this custom module is loading before the snipped and the url for ajax call is not defined.

In our case this was a bit of code in a default template which was loading the customer-data.js file after it had already been called on the success page.

We found file: vendor/magento/module-checkout/view/frontend/templates/success.phtml

was loading this code:

<script>
 require([
 'Magento_Customer/js/customer-data'
 ], function (customerData) 
 var sections = ['cart'];
 customerData.invalidate(sections);
 customerData.reload(sections, true);
 );
</script>

Removing this code fixed it, which we did by creating a copy of this file in our theme templates directory and removing the offending code snippet.

You can use Chrome Dev tools to find out where the error was happening and then just before in that file on your local dev add in a console.trace(); call to establish what was calling the function which is throwing the error in the console. Follow the chain to where you are loading things improperly.

Fixed this using window on load:

 <script type="text/javascript">
require([
 'jquery'
 ],
 function($) 
 $(window).on("load", function() 
 require([
 'Magento_Checkout/js/model/cart/totals-processor/default',
 'Magento_Customer/js/customer-data',
 'Magento_Checkout/js/model/quote',
 'Magento_Checkout/js/model/shipping-rate-processor/new-address',
 'Magento_Checkout/js/model/shipping-rate-processor/customer-address',
 'Magento_Checkout/js/model/shipping-rate-registry'
 ], function(defaultTotal, customerData, quote, defaultProcessor, customerAddressProcessor, rateRegistry) 
 $(document).ready(function() 

 /** Do your code here */
 );

 );
 );
 );
</script>

I had previously removed "content" container from theme.xml,
I fixed it by adding following code to theme.xml

<referenceContainer name="content">
 <block name="customer.section.config" class="MagentoCustomerBlockSectionConfig"
 template="Magento_Customer::js/section-config.phtml"/>
 <block name="customer.customer.data"
 class="MagentoCustomerBlockCustomerData"
 template="Magento_Customer::js/customer-data.phtml"/>
</referenceContainer>