This issue was discussed before in https://www.drupal.org/node/2854584 and it was reported as Fixed.
However it still exists, and it doesn't allow to save the "live credentials" even the test one are fine.
I had several conversations with PayPal customer support and the credentials are fine.

My PayPal: Premier Account, registered in the UK.

Comments

Londova created an issue. See original summary.

Londova’s picture

Londova CreditAttribution: Londova commented

It seems I succeed to make things happen.
Initially, I installed the credentials for "TEST" mode, which contain "facilitator_api".
After a few trial orders, I switched to "LIVE" mode and installed the proper credentials: "Seller preferences - API access - Update - View API Signature...".

I made 2 live paymets and it works. But this is NOT the proper way to get results. Thus additional investigations are necessary.

sumanthkumarc’s picture

sumanthkumarc CreditAttribution: sumanthkumarc at Azri Solutions commented
Parent issue: » #2862663: Cannot save Paypal ExpressCheckout if only account is live.

@Londova see this similar issue, looks same https://www.drupal.org/node/2862663

sumanthkumarc’s picture

sumanthkumarc CreditAttribution: sumanthkumarc at Azri Solutions commented

there is a patch at https://www.drupal.org/node/2862663#comment-12010806, can you test it once and comment there?

sumanthkumarc’s picture

sumanthkumarc CreditAttribution: sumanthkumarc at Azri Solutions commented
Status: Active » Closed (duplicate)

since that issue is old, i'm marking this issue as duplicate. Feel free to re-open if its different issue.