Ошибка non-static variable this cannot be referenced from a static context

//public void ExcelUpdate(String error, int ID) throws FilloException {
    Connection con2 = fillo.getConnection("E:\\QA Java\\LastQATraineeProject\\excelFiles\\SecondTable.xlsx");
    String data2;
    if (RegistrationPageC.ErrorAppeared(error)) {
        data2 = "Update Лист1 Set result = 'Successfully!' Where ID = " + ID + "";
    }
    else {
        data2 = "Update Лист1 Set result = 'Unsuccessfully!' Where ID = " + ID + "";
    }
    con2.executeQuery(data2);
    con2.close();
}

    
public String ErrorDisplay() {
    return ErrorWindow.getText();
}
    
public boolean ErrorAppeared(String error) {
    if (ErrorDisplay().contains(error)) {
        Assert.assertEquals(ErrorDisplay(), error);
        return false;
    }
    else {
        return true;
    }
}