Unexpected protocol character from backend

I'm trying to use large objects from Borland C++ Builder via ODBC. Large
object wasn't created with an error message "Unexpected protocol character
from backend". This is quotting from mylog.log file:

[...]
SQLPutData: (1) cbValue = 8192
send_function(): conn=51460548, fnid=957, result_is_int=1, nargs=1
send_function: done sending function
  arg[0]: len = 4, isint = 1, integer = 393216, ptr = 393216
    done sending args
SOCK_flush_output: self->buffer_out = F , self->buffer_filled_out = 19,
written = 19
  after flush output
   got id = Z
send_function: error - Unexpected protocol character from backend
OID: 0
STATEMENT ERROR: func=SQLPutData, desc='', errnum=1, errmsg='Couldnt create
large object.'
CONN ERROR: func=SQLPutData, desc='', errnum=6, errmsg='Unexpected protocol
character from backend'
**** SQLError: henv=0, hdbc=0, hstmt=51475184
SC_get_error: status = 1, msg = #Couldnt create large object.;
Unexpected protocol character from backend#
       szSqlState = '08S01', szError='Couldnt create large object.;
Unexpected protocol character from backend'
**** SQLError: henv=0, hdbc=0, hstmt=51475184
       returning NO_DATA_FOUND
[...]

Couldn't anybody tell me please where can I get information about the
"protocol character".

Thank you, Mikhail.