Can someone help me with the reason I am getting this message testing with the PayPal sandbox?
 
"This invoice has already been paid. For more information, please contact the merchant."
 
Thanks
Will

You need to confirm the business email address and business bank account.

Well, it is a "Sandbox" test account, so the email and bank account should already be setup right?
Is there something with that test account that I'm doing wrong?
 
Thanks for helping.
Will

Also sandbox accounts need to have a confirmed email and bank account. This is separate from other accounts.

Dick
Can you explain this in a bit more detail? im having exactly the same problem and dont quite understand your last response to the guest user.
 
Is this error occuring within paypals systems or on callback to viart due to a conflict of values between the two systems?
 
Sorry.. rather lost as to where to go on this right now and also need to get it working quite urgently...

I'm jump in here and offer my LIMITED experience with using PayPal's sandbox. (So keep that in mind when you determine if my comments are valuable.)
 
From what I recall, every account that you use in the sandbox must be created IN the sandbox.
 
Specifically, I needed to create an admin account IN the sandbox area (the info that's used in the shopping cart) and I also needed to use the sandbox area to create fake customer accounts as well, because REAL (valid) PayPal customer accounts were not recognized.
 
It also seems that the test (customer) accounts that I created needed to be "validated" by email... yet NO emails ever arrived. Instead, the Sandbox has it's own INTERNAL email area where the newly created sandbox user accounts are validated.
 
Again... my recollections of what I needed to do over a year ago are somewhat (very) fuzzy, and things may have changed since then.
 
But one thing that's NOT fuzzy, and that I *do* vividly recall.... the PayPal sandbox is cranky, buggy, poorly programmed, difficult to use, difficult to understand, and counter-intuitive.
 
Eventually I just gave up and did my final testing on the LIVE PayPal site. I used a trusted friend's (seldom-used) PayPal account, I made REAL purchases that resulted in REAL charges to credit card that he rarely used... and after each test I'd refund the purchase.
 
NOTE: Before the testing started, my friend telephoned his credit card provider to alert them to the fact that he was helping me to test my cart. He let them know WHO the charges were coming from and that the series of charges/refunds were NOT to be flagged as suspicious activity.
 
GOOD LUCK!