IO Error whenever page is named contact.html

I tried validating several websites, and noticed that whenever page is
called contact.html I am getting the following

1.      IO Error: HTTP resource not retrievable. The HTTP status from the
remote server was: 409.

https://www.usa-travel.us/contact.html

Here is a screenshot:



I checked that on several websites with consistent results which only
affects pages named contact.html.  Even when I renamed perfectly validated
page to be named contact.html that page stops being validated.

Could you please let me know what is going on?

Thank you in advance.

Leonid Batkhan

 

 



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