When testing Magento integration, channel returns error: 

SOAP-ERROR: Parsing WSDL: Couldn't load from '' : failed to load external entity ""


There are 3 possible reasons for this error to appear:

1. Web hosting provider does not support loopback connection which is essential for Magento to operate.
- Contact the provider and ask them to confirm whether or not loopback connection is supported.

2. Magento store cannot connect to itself to load external entity ""

- Enable WSDL caching in Magento backend: System > Magento Core API > Enable WSDL Cache set it "Yes".

3. Magento is heavily loaded and has performance issues, thus, the request cannot be processed and a timeout occurs. 

- Try again later.