Message: Unable to connect to the merchant

Can you access the URL callback from the browser?
It should give an error message - not a 404.
When I type URL calback page i receive an error message saying that the order is not submited.

Did you change IP address lately?
I changed the IP about 2 months ago, but i last payment was received one week ago.

This is reply from Realex re this error

There are a few possible causes of this type of error:

1. A scripting error in your response page may cause this error, depending on the language in which you have coded your response script – for example, an implementation in ASP.NET which contained a simple syntax error would result in a server response of HTTP 500 – Internal Server Error. This would cause the response process to fail. I would suggest to visit our resource centre at https://resourcecentre.realexpayments.com/ where you can download sample code in a variety of languages for comparison.

2. Some server configurations allow automatic redirection to another resource on the server. Please note that the use of automatic redirection from your nominated response page to another resource on your server will cause the response page to fail. If you have a requirement to redirect your customers automatically to another page on your servers following the transaction, we recommend that you implement this using javascript – a simple hidden HTML form can be submitted automatically using Javascript, redirecting your customer as required. Server level automatic redirects will cause this error to be generated

3. A response script which generates no output would also be a possible cause. If our response process connects to your response page successfully, but the response page produces no output after connection, the system will interpret this as a failure to connect and output the error message described above. Please ensure that your response page produces at least some output – we suggest a link for the customer to click to continue shopping.

4. Finally, if your response page is not openly available to connections across the internet, the response process will fail.

It may be a good idea to check your firewall settings to ensure that our server can connect to your website.

Here is a copy of the logs which may be useful in determining the problem:

$VAR1 = bless( {
''_protocol'' => ''HTTP/1.1'',
''_content'' => ''

Page not found |

I've made this change and contacted realex to use 'www' version, but again, I'm receiving the same error message.

The error message from Drupal says: Hash match failed for order.

cart/uc_realex/complete

I did some research on realex site so I've found this:
Result: 511
Message: Unable to connect to the merchant, response URL: http://mysite.com/cart/uc_realex/complete

The original Drupal message is:
Your transaction has been successful but there was a problem connecting back to the merchant's web site. Please contact the merchant and advise them that you received this error message. Thank you.

Maybe there is a problem with order ID, because you have

watchdog('uc_realex', t('Hash match failed for order @order_id.')

but in logs I've found: Hash match failed for order .

PS. Thank you for testing.

After your testing I received three messages like:

Date Monday, February 27, 2012 - 18:28
User Anonymous
Location http://www.sample.com/cart/uc_realex/complete
Referrer
Message 403.shtml
Severity warning

Reponse from Realex:

The 511 alert is caused when the user's browser cannot be directed back to your response page. It will not prevent the transaction from actually going through; the transaction will process successfully. This would not be caused by an incorrect shared secret. It is also very unlikely that we are not sending back the order number as if this was the case; it would not be limited to just one merchant.

511 alerts are often caused by issues on the response page. I have had a quick look at your response code but it is difficult to tell where a problem might be occurring. I suggest turning on the PHP logs in order to make debugging easier.

Compatibility notes:

mod_security - if mod_security is enabled, you might have problems connecting back to the website because an http error is returned immediately (error 503, 403 or something else).