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BC30387_Class 'default_aspx' must declare a 'Sub New' because its base class '_Default' does not have an accessible 'Sub New' that can be called with no arguments.

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User1717218719 posted

Hi all I am recieving the error

"BC30387 Class 'default_aspx' must declare a 'Sub New' because its base class '_Default' does not have an accessible 'Sub New' that can be called with no arguments."

I am unsure of what it means ad how to fix it any help would be great thanks.

My code is below:

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
  <title>Uploaded Files</title>
</head>
<body>
  <form id="form1" runat="server">
    <div>
      <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataSourceID="odsFiles" OnRowDataBound="GridView1_RowDataBound" >
        <Columns>
          <asp:BoundField DataField="Id" HeaderText="Id" SortExpression="Id" />
          <asp:BoundField DataField="OriginalName" HeaderText="OriginalName" SortExpression="OriginalName" />
          <asp:BoundField DataField="ContentType" HeaderText="ContentType" SortExpression="ContentType" />
          <asp:BoundField DataField="DateCreated" HeaderText="DateCreated" SortExpression="DateCreated" />
          <asp:HyperLinkField DataNavigateUrlFields="Id" DataNavigateUrlFormatString="~/DownloadFile.aspx?Id={0}" HeaderText="Download" Text="Download" />
        </Columns>
      </asp:GridView>
      <br />
      <br />
      <asp:Button ID="btnAddNew" runat="server" OnClick="btnAddNew_Click" Text="Add New File" /><br />
        <br />
<%--        <asp:Button ID="BttnSave" runat="server" OnClick="BtnSave_Click" Text="Save" />--%>
        <br />
      <br />
      <asp:ObjectDataSource ID="odsFiles" runat="server" SelectMethod="GetList" TypeName="FileInfo" />
    </div>
  </form>
</body>
</html>

Wednesday, February 5, 2020 11:30 AM

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User1120430333 posted

It means that you modify default.aspx.cs to have a Sub New, a class constructor with no parms being used, becuase the _Default that default.aspx.cs is in inheriting from does not have a Sub New that takes no parameters.

This is object oriented programming 101 that should be aware of and know.

https://www.tutorialspoint.com/vb.net/vb.net_classes_objects.htm

<copied>

Constructors and Destructors
A class constructor is a special member Sub of a class that is executed whenever we create new objects of that class. A constructor has the name New and it does not have any return type.

<end>

http://www.informit.com/articles/article.aspx?p=25742&seqNum=8

Wednesday, February 5, 2020 8:27 PM
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User288213138 posted

Hi E.RU,

"BC30387 Class 'default_aspx' must declare a 'Sub New' because its base class '_Default' does not have an accessible 'Sub New' that can be called with no arguments."

The error is due to a derived class does not declare a constructor, and Visual Basic cannot generate one because there is no base class constructor it can call.

You can try to below method:

1.Declare and implement at least one Sub New constructor somewhere in the derived class.
2.Add a call to a base class constructor, MyBase.New(), as the first line of every Sub New.

More information about this error you can refer to this link:

https://docs.microsoft.com/en-us/dotnet/visual-basic/misc/bc30387

Best regards,

Sam

Thursday, February 6, 2020 9:40 AM
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User1717218719 posted

Hi Samwu

Thanks for your reply.

I have tried to Declare and implement at least one Sub New constructor by doing the following:

Dim AZBlob As New _Default(ConfigurationManager.AppSettings(StorageConnStr), containerName) Await AZBlob.UploadAsync(originalName, cancelToken)

However I recieve the error "Type _Default is not declared". Do you know why this might be ?
Friday, February 7, 2020 8:13 AM

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BC30387_Class 'default_aspx' must declare a 'Sub New' because its base class '_Default' does not have an accessible 'Sub New' that can be called with no arguments.

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