grep -r -l "SALES_ORDER_CUSTOMER_ID_CUSTOMER_ENTITY_ENTITY_ID"
I was able to narrow down the file (db_schema.xml ) file responsible in the db update script when running
"bin/magento setup:upgrade"
As I was not able to find any relevant information and cross checking a similar error comment I found in researching the issue, I commented the following code in var/magento/module_sales/etc/db_schema.xml
comment out constraints from 253 to 268
<!--
<constraint xsi:type="foreign" referenceId="SALES_ORDER_CUSTOMER_ID_CUSTOMER_ENTITY_ENTITY_ID" table="sales_order"
column="customer_id" referenceTable="customer_entity" referenceColumn="entity_id"
onDelete="SET NULL"/>
<constraint xsi:type="foreign" referenceId="SALES_ORDER_STORE_ID_STORE_STORE_ID" table="sales_order" column="store_id"
referenceTable="store" referenceColumn="store_id" onDelete="SET NULL"/>
-->
Then I restarted server/ httpd
Finally
php bin/magento setup:upgrade
No more error. However I believe this is a workaround fix until I am able to get better guidance from magento team.