In our recent upgrade from 5.0 to 5.1.47, the new version behaves differently and it screw up character set when user submit info from our web app powered by .NET.
After digging around for a afternoon, this is how to fix it:
And add those lines to the config:
init_connect='SET collation_connection = utf8_general_ci'
init_connect='SET NAMES utf8'
There are other options for collation besides utf8_general_ci such as utf8_unicode_ci. See this article: