An Error Occurred When Obtaining The Payment Method Configuration

Getting this error when setting up Paypal Express Checkout. The authorisation works etc - then when I click the "go back to CS-Cart" link I get error. Any ideas?

What is error text?

This exactly, nothing else

An Error Occurred When Obtaining The Payment Method Configuration

Everything is correct, I connect to Paypal, it connects to CS-Cart and authories, but when I click back to cs-cart I get that error

Success - [url=https://postimg.cc/0bQJ1z84]success.jpg[/url]

Error - [url=https://postimg.cc/xkKX3HRX]error.jpg[/url]