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.NET / VB.Net Troubleshooting

'NNNN' is not declared (VB.NET)


When compiling a VB.Net application the compiler generates the following error:

error BC30451: 'NNNN' is not declared. It may be inaccessible due to its protection level.

Visual Studio 2010 simply gives the error:

'NNNN' is not declared. It may be inaccessible due to its protection level.

or with older versions of Visual Studio (i.e. up to and including Visual Studio 2008): 

Name 'NNNN' is not declared.

where 'NNNN' is the name of a variable.

If you are using C# then the error message is slightly different (but means the same thing):

The name 'NNNN' does not exist in the current context

in this case please refer to the C# version of this article "The name NNNN does not exist in the current context".

Possible Cause 1: (see also Possible Cause 2 below)

The compiler does not recognise the variable 'NNNN'. This is either because the variable name is misspelt or because the compiler could not find a corresponding definition.


  • A common cause is a simple misspelling where the identifier is used. For example:
dim number as Integer
numbr = 1

Here the identifier is defined as 'number' but used in the code as 'numbr'. The solution is to correct the spelling.

  • If the name is referring to an identifier then it may be that the reference simply needs to be qualified. For example:
Imports System.Web.HttpContext
Module Example
    Function ExampleProc() as String
        return Application("name")
[Error] Name 'Application' is not declared.

Try replacing "Application" with "Current.Application".

  • The most common cause is that the namespace that defines the name is missing. Identify and import the required namespace - the table below should help.

    For example, with the error:

    Name 'Directory' is not declared.

    The missing namespace is System.IO, so the solution is to add:

    Imports System.IO

    at the top of the file.

    The following table (which is not exhaustive) lists identifiers together with the namespace and any qualification that might typically be required:

    Name Namespace Common Qualified Name
    Abs Math Math.Abs
    AnchorStyles System.Windows.Forms  
    Application System.Windows.Forms
    For Windows forms applications.
    For web applications.
    ApplicationDeployment System.Deployment.Application  
    Assembly System.Reflection  
    BindingFlags System.Reflection  
    CultureInfo System.Globalization  
    Cache System.Web.Caching  
    CipherMode System.Security.Cryptography  
    ConfigurationManager System.Configuration
    Also ensure project contains reference to System.Configuration.dll
    Current System.Web.HttpContext  
    Debug System.Diagnostics  
    Debugger System.Diagnostics  
    Dns System.Net  
    Directory System.IO  
    Encoding System.Text  
    EventLog System.Diagnostics  
    File System.IO  
    FormsAuthentication System.Web.Security  
    HostingEnvironment System.Web.Hosting  
    HtmlEncode System.Web.HttpUtility  
    HttpContext System.Web
    Also ensure project contains reference to System.Web.
    HttpRuntime System.Web  
    HttpStatusCode System.Net
    HttpUtility System.Web  
    ImageFormat System.Drawing.Imaging  
    Marshal System.Runtime.InteropServices  
    NormalizationForm System.Text  
    PaddingMode System.Security.Cryptography  
    Parallel System.Threading.Tasks  
    Path System.IO  
    Process System.Diagnostics  
    Regex System.Text.RegularExpressions  
    Request System.Web.HttpContext Current.Request
    Round Math Math.Round
    SecurityElement System.Security  
    SecurityMode System.ServiceModel  
    SecurityZone System.Security  
    Server System.Web.HttpContext Current.Server
    ServicePointManager System.Net  
    SmptMail System.Web.Mail  
    SslPolicyErrors System.Net.Security  
    Stopwatch System.Diagnostics  
    ThreadPool System.Threading  
    UnicodeCategory System.Globolization  
    UrlDecode   HttpContext.Current.Server.UrlDecode
    User   HttpContext.Current.User
    UTF8Encoding System.Text  
    VirtualPathUtility System.Web  

    It is my intention to add to this table over time.

Possible Cause 2:

A less likely cause is that the project itself lacks a reference to the necessary library. This can arise when (for example) creating a class library and using web namespaces, for example:

Name 'HttpContext' is not declared


Name 'HttpRuntime' is not declared

even though the line "imports System.Web" is included.


Add the reference to the project:

  1. Right click the project in the solution explorer and select "properties".
  2. On the "References" tab ensure that the required namespace is listed under "References" (do not confuse this with "Imported namespaces", the important thing is that it must be listed under "References".)

The necessary references are listed in the table above (shown under "Possible Cause 1"). For example the solution to "HttpContext (or HttpRuntime) is not declared" even though "Imports System.Web" is included in the file is to ensure that "System.Web" is listed as one of the project References.

These notes are believed to be correct for VB.NET for .NET 4, .NET 3, .NET 2 and .NET 1.1 frameworks, and may apply to other versions as well.

For the corresponding C# version of this article please see "The name NNNN does not exist in the current context".

About the author: is a dedicated software developer and webmaster. For his day job he develops websites and desktop applications as well as providing IT services. He moonlights as a technical author and consultant.