Npgsql and 57014 query_canceled error message

I'm doing some testing on a larger dataset, and I've started getting a
57014 error message when I catch an NpgsqlException.  I thought it
might be timing out on me, so in the connection string I've set the
time out settings to the maximum of 1024 seconds before timeout.

Has anyone else experienced this, and is there a known solution?
Thank you.

regards,
Karen