When doing direct Paypal Payouts from our dashboard, there are a few errors that occur more often. Here we'll explain some of them.
You need to top up your Paypal balance from your bank account since Paypal allow bulk payments to be made only from available balance. Note: The balance needs to cover the payouts fees as well (non-domestic fees are higher) so we recommend having a balance of at least 2% more than what you need to pay.
Personally, I would top up maybe 2-3 months worth of payouts (estimating from last months) to not do that every month.
It happens mostly when you're not allowed to access the Payouts API. Go to Paypal Developers page and Log In to the developer dashboard, click on "My account" on the left and scroll down until you see the "Permissions" table. Check if on the last row "Payouts" is marked with a green checkmark. If not ask Paypal to enable it.
Some other causes even if you have Payouts enabled:
your Paypal account is not verified
you don't have a bank account linked
your linked bank account is not verified
In any case, you should contact Paypal about it to help you out.
(At payment level) The Paypal email for that user is not found. Most likely that affiliate enter the wrong Paypal address or he/she doesn't have a Paypal account with that email. You'll need to contact the affiliate to update his Paypal email to correct one.
(At payment level) The Paypal email of that user is not confirmed. User registered to Paypal but hasn't confirmed the email. The payment will remain as unclaimend in your Paypal dashboard until the user confirms their email. You can also cancel the payment if you want.
Paypal got an internal error while processing this payout request. Try again in a few minutes.
The PayPal risk/fraud engine has decided to decline processing the payment.
There could be several things, or some combination of things that triggered the alarm. If most of your payouts are OK and only some are declined it is likely (primarily) issue(s) with the other parties' PayPal accounts, not your account.
You can contact PayPal to see if they can give you some specific reason, but this isn't a technical problem and does not have a technical fix.