EF Core BulkInsert 'Object reference not set to an instance of an object.'

Question

My EF Core BulkInsert throws error when inserting more than 80 rows, below is the example insert 80 rows data
Insert 80 rows

but when i try 100rows the error as shown

System.NullReferenceException: 'Object reference not set to an instance of an object.'

Im using JSON for the data

function Save() {
    var fail = {
        title: 'Data insert fail',
        message: 'refresh page to save again',
        position: 'topRight'
    };
    console.log(_oSeismics);
    if (_oSeismics.length > 0) {
        var ajaxRequest = $.ajax({
            url: "../PmepTempAdd/SavePmepVSP/",
            type: "POST",
            data: { data: _oSeismics },
            dataType: "json",
            beforeSend: function () {
            },
        });

        ajaxRequest.done(function (data) {

            swal('Success!', 'Successfully saved.', 'success');

        });

        ajaxRequest.fail(function (jqXHR, textStatus) { 
            iziToast.error(
                    fail
                ); 
        });

    }

    else {

        iziToast.error(
                    fail
                );

    }

}

function NewSeismicObj() {
    var now = new Date();
    var date = now.getFullYear() + '-' + (now.getMonth() + 1) + '-' + now.getDate();
    var time = now.getHours() + ":" + now.getMinutes() + ":" + now.getSeconds();
    var dateTime = date + ' ' + time;

    console.log(dateTime)
    
    var oSeismic = {
        
        No: "",
        WellName: "",
        SurveyVspYaTdk: "",
        VspSonicCalibrationSynthetic: "",
        VspReport: "",
        VelocityWellCheckshot: "",
        WellProgramProposal: "",
        FinalWellReportEndOfWellReport: "",
        ProcessingDataSgy: "",
        RawDataSgy: "",
        Recommendation: "",
        RowCreated: dateTime
            
    };console.log(dateTime)

    return oSeismic;

}

Any Idea whats wrong with this code? for 80 rows runs normal, but over 80 error shown as above

Edit :

I have tried to change parameter into data but still error

PmepTempAddController.cs code

public JsonResult SavePmepVSP(List<VerTempPmepSeismicVsp> data)
    {
        _VSPt = _db.SavePmepSeismicsVSP(data);
        TempData["success"] = "Inserted to TempPmeporary Table successfully";
        return Json(_VSP);
    }

Service.cs code

    public List<VerTempPmepSeismicVsp> SavePmepSeismicsVSP(List<VerTempPmepSeismicVsp> data)
    {
        _dbContext.BulkInsert(data);
        return data;
    }

Answer 1

Sometimes Its also depends on which parameter are you using...

 var ajaxRequest = $.ajax({
            url: "../PmepTempAdd/SavePmepVSP/",
            type: "POST",
            data: { data: _oSeismics },
            dataType: "json",
            beforeSend: function () {
            },
        });

here you have written data: { data: _oSeismics }, So, in the backend, it must have something like the below...

public List<VerTempPmepSeismicVsp> SavePmepVSP( List<VerTempPmepSeismicVsp> data) 

Note: Look at the name of parameter.