I keep getting "(Test Mode) Unknown Error: Error code 0"
 
Does anybody know what this means? Have you gotten this error? How am I supposed to fix an unknown error?
 
Thanks for any help!

This was using the account in Test Mode with the test card number 4222222222222. I tried using a real account number, and didn't get the error. Still don't know why I was getting the error using the test number (which I would prefer to using a real credit card).

It could be that the server doesn't like that particular Visa test card number as its 13 digits. Have you tried others? Theres a list at this site http://www.crazysquirrel.com/finance/test-cc.jspx

That's true. That is the one that the Authorize.net AIM manual indicates should be used, but I wonder if ViArt maybe only sends 16 digits, or something... ?
 
The 16 digit VISA card 4111111111111111 did work. Thanks!
 
Still though... fishy...

Just for reference, I ran into this problem. The 4222222222222 number uses the x_amount as the error code to return. If the x_amount is not a valid error code, it will throw that error.

I faced the same problem of Unknown error with Authorize.net, i tried with 4111111111111111 and it worked for me. Thanks for the above information.

Use the following TEST credit card to do your authorizenet test.
 
Credit card type : MasterCard.
Credit card :- 5424000000000015
 
Use any name as a card holder name and use any date after current date as exp date of cc.
 
(VISA with 4222222222222 did not work at my end.)