How to fix the synchronization error 1s database and online store?

Question

Data synchronization

Colleagues, hello!
Has anyone come across this problem and can you help me figure out how to proceed.
We are trying to synchronize the online store and the database of goods from 1c. On side 1c, the following error is generated:

Uploading to the site ended with errors.
import.xml: A server-side error has occurred. Unknown import status received.
Server response:
/* Copyright (c) 2010, Yahoo! Inc. All rights reserved. Code licensed under the BSD License: developer.yahoo.com/yui/license.html */

and on the server in the error logs there is not even information that something was trying to synchronize.

no server side errors: [[email protected] /]# cat /var/www/httpd-logs/mydomain.error.log | grep -v 'buffered to a temporary file' | wc -l
0

There is a suspicion that the server is simply incorrectly configured, but what exactly - I can not understand. hosting support (reg.ru) says that there are no errors and you need to understand 1s. Has anyone come across this and can help? not for free.