BUG #14430: NPGSQL error

The following bug has been logged on the website:

Bug reference: 14430
Logged by: zeinab mokdad
Email address: zmokdad(at)vanrise(dot)com
PostgreSQL version: 9.6.1
Operating system: Windows
Description:

trying to bulk insert in STDIN an error is raise : COPY file signature not
recognized
note that this was working fine in Npgsql2.0 when upgrading and using
BeginRawBinaryCopy this error is raised.
this is my code :
string r = @"961\t8\t * ****\t3\t0\t0\t1\t11 / 23 / 2016 2:33:35
PM\t8\t1\t1\t100\t100\t0\t100\t0\t0\t0\t0\t0";
data = GetBytes(r);
using (var outStream = conn.BeginRawBinaryCopy("COPY BINARY
rt197_temp FROM STDIN"))
{
outStream.Write(data, 0, len);
}

is there any special way to determine fields seperator or EOF.