Things don't appear to be working at the moment. 9.5.9 TYPO3

[lifecounter]

"Things don't appear to be working at the moment. Please try again later." is the message PayPal throws after checkout, no matter what I do.
I use cart with cart_products in a 9.5.9 TYPO3.

[martinbyd4m]

I`ve got the same issue, with TYPO3 9.5.17

Is there any configuration for the api-credentials, except the business email?

[robertpie]

I`ve got the same issue, with TYPO3 9.5.20

Did you find a solution?

[robertpie]

I got it working:

1. in SITES CONFIGURATION I replaced a simple / with the full domain name (https://xxx.yy/)
2. Added the following variables to [FE][cacheHash][excludedParameters]: cHash, amt, cc, st, tx

TYPO3 9.5.20
cart_paypal 4.0.2