Updated DNP Portal assemblies to fix 2CheckOut passback issue.
1. First of all please create entire "bin" folder backup of DNP Portal;
2. To install service pack extract all files to "bin" folder of DNP Portal with replace option enabled;
3. In case of any issues with SP2 please restore "bin" folder content from a backup you've created in #1 and send issue description at support@dotnetpanel.com;