Why did I get the error "User authentication failed" or "Merchant identification error"?

The account information passed does not match the login information. 

Check that your website, shopping cart and/or application are sending the following fields correctly. These fields are case-sensitive: 

• USER - This field contains the Payflow Pro login name. This field is the same as VENDOR unless you set up a separate user for your Payflow transactions.
• VENDOR - This field contains the Payflow Pro login name. This is the login ID you created when you signed up for the Payflow Pro service and is the same merchant ID used to access PayPal Manager. 
• PARTNER - This field contains either VeriSign, PayPal, or the name (ID) of the reseller or company from which you purchased Payflow Pro. If you use Payflow Link, you must pass this field to authenticate your account. Add the following line to your HTML code: 
  < INPUT type=hidden value=" name=PARTNER >
  
  Note: If you use Miva Merchant 4.x or earlier, include the partner and vendor within the User ID field (for example, xuser&PARTNER=xpartner) or enter the partner ID within the URL string (for example, https://payflowlink.paypal.com?&PARTNER=partner name).
• PWD - This field contains your Payflow Pro password. This can be the same password that you use to access PayPal Manager. The password must be strong, between 6 and 32 characters long, and include at least one number. 
  
  Note: Although PayPal Manager allows special characters in the password, avoid using them as some operating shells like DOS or UNIX treat them differently. For example, the percent sign (%) is a special character within DOS. A password such as "PaSS%word1" will truncate to "PaSS" because DOS will drop all the characters after the second "S". 

Test transactions are posting to live servers. 

Test account users can post transactions to the live servers only after the account is activated. Modify your website or e-commerce application to send transactions back to the test servers. Review testing Payflow transactions.

Contact your merchant bank and obtain account information for your processor using the Processor Setup Guide. The account administrator must send this information to payflow-support@paypal.com. After we update your processor information, you will receive a notification email from Payflow Support.

Contact your merchant bank and obtain account information for your processor using the Processor Setup Guide. The account administrator must send this information to payflow-support@paypal.com. After we update your processor information, you will receive a notification email from Payflow Support.

An IP address security feature was implemented. The Allowed IP Address security feature blocks all transactions coming from IP addresses that aren't on the Approved list. This generates the "User Authentication Failed" error because the IP address is invalid. 

Verify that any IP address entered in PayPal Manager is static. Even though you set the IP address to the static IP you got from your hosting company, the error can still occur if your web server isn't on a single static IP. Your website may be hosted on a web or server farm that allows the hosting company to define your website as a virtual server. If that's the case, contact your hosting company to get the IP address or range of addresses that your website uses. Type these IP addresses in the approved list under "Allowed IP Address" for API transaction processing in PayPal Manager. This makes the server farm able to process transactions through your Payflow Pro account.

The system is sending Recurring Billing transactions. 

Change the URL of the server back to the test server or activate the Recurring Billing Service on the account. 

Transactions are sent to a different Payflow account or processor. 

This error usually occurs under the following circumstances: 

• The credit transaction was sent to a different account than the account involved in the sale or delayed capture
• During a delayed capture transaction, the request was sent to a different account than the authorization

In both cases, the original transaction and the secondary request were sent to different processors. If a credit or delayed-capture transaction is sent to a different Payflow Pro account than the original transaction, resubmit the transaction to the same account on which the original transaction was performed.