Authorize.net PHP SDK pre-authorization with $0 amount is not working

[JohnSonandrla]

I need to be able to pre-authorize transactions using authOnlyTransaction method for $0 and the API responds with code 290 "There is one or more missing or invalid required fields". I tried changing amount to $0.01 everything works as expected but with $0. I do have another authorize.net account using the old deprecated AIM and it's working fine there (th same processor). According to Authorize.net this is not related to processor limitation as they do not see $0 transactions hitting their system at all... any ideas?

According to documentation I probably need to set isFirstSubsequentAuth to true but I cannot find the right method that would do that

[ReyesHatrinak]

Yes, I think you want Secure Acceptance Hosted Checkout API documented here. See page 51 for all the endpoints. If you only want to create a token then the test endpoint is testsecureacceptance.cybersource.com/token/create /echatspin /echatrandom

Follow the below steps to get a new signature key. To know more about the signature key, visit here.

1. Log into the Merchant Interface at https://account.authorize.net.
2. Click Account from the main toolbar.
3. Go to Settings in the main left-side menu.
4. Click API Credentials & Keys.
5. Select New Signature Key. Review the options available.
6. Click Submit and continue.
7. Request and enter the PIN for verification.
8. Your new Signature Key will be displayed that is to be copied to add to your Magento Admin configuration.

1. Update Magento admin configuration
   1. Log in to the admin panel.
   2. Go to Stores > Configuration.
   3. Click Sales > Payment Methods.
   4. Expand the Authorize.net Direct Post section.
   5. In the Signature Key enter the SHA-512 Signature Key.
   6. Click Save Config.