I have a Magento 1.9 CE installation that was recently upgraded from 1.7. Authorize.net direct post worked in 1.7, but now it does not work. When I try to checkout, I get the standard message about "Response hash validation failed. Transaction declined."

I made a new hash key and entered it in both Magento and authorize.net. I then cleared the Magento cache. I still get this error though. I rebooted the server. I tried a different browser. Any thing I am missing?

  • One difference between 1.7 and 1.9 was the inclusion of a tax rule. I noticed over on this thread (magento.stackexchange.com/questions/4001/…) towards the end, person mentions that if submitted value is different, it can throw this error. I have been noticing with the tax rule, before a user logs in, or an address is selected, tax is calculated and shows up in the subtotal. So I deleted my tax rule, but it did not seem to have any impact.
    – MLindsay
    Commented Jul 22, 2014 at 23:39

1 Answer 1


This error occurs in the function Mage_Authorizenet_Model_Directpost::validateResponse. What this code does is checks for a trans_md5 and login set in the config and then validates them against the response.

public function validateResponse()
    $response = $this->getResponse();
    //md5 check
    if (!$this->getConfigData('trans_md5') || !$this->getConfigData('login') ||
        !$response->isValidHash($this->getConfigData('trans_md5'), $this->getConfigData('login'))
    ) {
            Mage::helper('authorizenet')->__('Response hash validation failed. Transaction declined.')
    return true;

What I would suggest is to step through this function and see what data causes the error.

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