DATABASE_QUERY_ERROR - Create leads operation

I am trying to create new lead via webservice but receiving error json response.

"error": {
"code": "DATABASE_QUERY_ERROR",
"message": "Database error while performing requested operation"
}

It only happens on create operation, update operation is still working fine. I appreciate all of your advices, thanks.
I am using pilot Vtiger 7.4 version, self hosted.

Edit the MySQL my.cnf file

bash

sudo nano /etc/mysql/my.cnf

Add the following to the end of the file:

bash

[mysqld]

sql_mode = NO_AUTO_VALUE_ON_ZERO

Restart the MySQL service

bash

sudo service mysql restart