C# Visual Studio 2008 - Design-Time Error in the Windows Forms Designer

How do you fix the Design-Time Error in the Windows Forms Designer?

When I click on MyMainForm.cs[Design] page to bring up the WinForms i get the following error:

  To prevent possible data loss before loading the designer, the following errors must be resolved: 
  The class name '?' is not a valid identifier for this language.     

  Instances of this error (1)  

  1.   Hide Call Stack 

  at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomParser.CodeTypeDeclarationFromCodeClass(CodeClass vsClass)
  at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomParser.OnNamespacePopulateTypes(Object sender, EventArgs e)
  at System.CodeDom.CodeNamespace.get_Types()
  at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomParser.Parse(TextReader codeStream)
  at Microsoft.VisualStudio.Design.Serialization.CodeDom.MergedCodeDomParser.System.CodeDom.Compiler.ICodeParser.Parse(TextReader stream)
  at System.CodeDom.Compiler.CodeDomProvider.Parse(TextReader codeStream)
  at Microsoft.VisualStudio.Shell.Design.Serialization.CodeDom.CodeDomDocDataAdapter.get_CompileUnit()
  at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager serializationManager)
  at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.DeferredLoadHandler.Microsoft.VisualStudio.TextManager.Interop.IVsTextBufferDataEvents.OnLoadCompleted(Int32 fReload)  

Here are my errors in MainForm.Designer.cs:

  Warning   1   The class name '?' is not a valid identifier for this language.     0   0   (No File Referenced, clicking on this warning does nothing) 
  Error 1   'CCP_Utility.MainForm' does not contain a definition for 'sourceFiles_Click' and no extension method 'sourceFiles_Click' accepting a first argument of type 'CCP_Utility.MainForm' could be found (are you missing a using directive or an assembly reference?) C:\Users\bmccarthy\Documents\Visual Studio 2008\Projects\CCP Utility\CCP Utility\MainForm.Designer.cs   84  67  CCP Utility
  Error 2   'CCP_Utility.MainForm' does not contain a definition for 'targetFolderPath_Click' and no extension method 'targetFolderPath_Click' accepting a first argument of type 'CCP_Utility.MainForm' could be found (are you missing a using directive or an assembly reference?)   C:\Users\bmccarthy\Documents\Visual Studio 2008\Projects\CCP Utility\CCP Utility\MainForm.Designer.cs   104 67  CCP Utility
  Error 3   'CCP_Utility.MainForm' does not contain a definition for 'sourceFolderPath_Click' and no extension method 'sourceFolderPath_Click' accepting a first argument of type 'CCP_Utility.MainForm' could be found (are you missing a using directive or an assembly reference?)   C:\Users\bmccarthy\Documents\Visual Studio 2008\Projects\CCP Utility\CCP Utility\MainForm.Designer.cs   118 63  CCP Utility
  Error 4   'CCP_Utility.MainForm' does not contain a definition for 'textBoxSourceDir_TextChanged' and no extension method 'textBoxSourceDir_TextChanged' accepting a first argument of type 'CCP_Utility.MainForm' could be found (are you missing a using directive or an assembly reference?)   C:\Users\bmccarthy\Documents\Visual Studio 2008\Projects\CCP Utility\CCP Utility\MainForm.Designer.cs   128 79  CCP Utility
  Error 5   'CCP_Utility.MainForm' does not contain a definition for 'textBoxTargetDirectory_TextChanged' and no extension method 'textBoxTargetDirectory_TextChanged' accepting a first argument of type 'CCP_Utility.MainForm' could be found (are you missing a using directive or an assembly reference?)   C:\Users\bmccarthy\Documents\Visual Studio 2008\Projects\CCP Utility\CCP Utility\MainForm.Designer.cs   138 79  CCP Utility
  Error 6   'CCP_Utility.MainForm' does not contain a definition for 'button_SaveSearch_Click' and no extension method 'button_SaveSearch_Click' accepting a first argument of type 'CCP_Utility.MainForm' could be found (are you missing a using directive or an assembly reference?) C:\Users\bmccarthy\Documents\Visual Studio 2008\Projects\CCP Utility\CCP Utility\MainForm.Designer.cs   151 74  CCP Utility
  Error 7   'CCP_Utility.MainForm' does not contain a definition for 'groupBox2_Enter' and no extension method 'groupBox2_Enter' accepting a first argument of type 'CCP_Utility.MainForm' could be found (are you missing a using directive or an assembly reference?) C:\Users\bmccarthy\Documents\Visual Studio 2008\Projects\CCP Utility\CCP Utility\MainForm.Designer.cs   164 66  CCP Utility

Let me know if you need to see some of my code to help me out

Here's the MainForm.Designer.cs file code:

namespace CCP_Utility
{
  partial class MainForm
  {
    /// <summary>
    /// Required designer variable.
    /// </summary>
    private System.ComponentModel.IContainer components = null;

    /// <summary>
    /// Clean up any resources being used.
    /// </summary>
    /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
    protected override void Dispose(bool disposing)
    {
        if (disposing && (components != null))
        {
            components.Dispose();
        }
        base.Dispose(disposing);
    }

    #region Windows Form Designer generated code

    /// <summary>
    /// Required method for Designer support - do not modify
    /// the contents of this method with the code editor.
    /// </summary>
    private void InitializeComponent()
    {
        this.button_Execute = new System.Windows.Forms.Button();
        this.listBox1 = new System.Windows.Forms.ListBox();
        this.folderPath = new System.Windows.Forms.Button();
        this.label1 = new System.Windows.Forms.Label();
        this.targetPath = new System.Windows.Forms.Button();
        this.targetFolderBrowserDialog = new System.Windows.Forms.FolderBrowserDialog();
        this.label3 = new System.Windows.Forms.Label();
        this.textBoxSourceDir = new System.Windows.Forms.TextBox();
        this.textBoxTargetDir = new System.Windows.Forms.TextBox();
        this.button_SaveSearch = new System.Windows.Forms.Button();
        this.groupBox2 = new System.Windows.Forms.GroupBox();
        this.buttonClearLog = new System.Windows.Forms.Button();
        this.buttonCancelSearch = new System.Windows.Forms.Button();
        this.sourceFileOpenFileDialog = new System.Windows.Forms.OpenFileDialog();
        this.sourceFolderBrowserDialog = new System.Windows.Forms.FolderBrowserDialog();
        this.textBoxSourceFiles = new System.Windows.Forms.TextBox();
        this.sourceFiles = new System.Windows.Forms.Button();
        this.SuspendLayout();
        // 
        // button_Execute
        // 
        this.button_Execute.Font = new System.Drawing.Font("Microsoft Sans Serif", 8.25F);
        this.button_Execute.Location = new System.Drawing.Point(12, 148);
        this.button_Execute.Name = "button_Execute";
        this.button_Execute.Size = new System.Drawing.Size(114, 23);
        this.button_Execute.TabIndex = 11;
        this.button_Execute.Text = "Search";
        this.button_Execute.TextAlign = System.Drawing.ContentAlignment.TopCenter;
        this.button_Execute.UseVisualStyleBackColor = true;
        // 
        // listBox1
        // 
        this.listBox1.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)
                    | System.Windows.Forms.AnchorStyles.Left)
                    | System.Windows.Forms.AnchorStyles.Right)));
        this.listBox1.Font = new System.Drawing.Font("Calibri", 11.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
        this.listBox1.FormattingEnabled = true;
        this.listBox1.ItemHeight = 18;
        this.listBox1.Location = new System.Drawing.Point(21, 220);
        this.listBox1.Name = "listBox1";
        this.listBox1.Size = new System.Drawing.Size(743, 184);
        this.listBox1.TabIndex = 15;
        this.listBox1.SelectedIndexChanged += new System.EventHandler(this.listBox1_SelectedIndexChanged);
        // 
        // folderPath
        // 
        this.folderPath.Location = new System.Drawing.Point(12, 59);
        this.folderPath.Name = "folderPath";
        this.folderPath.Size = new System.Drawing.Size(117, 23);
        this.folderPath.TabIndex = 1;
        this.folderPath.Text = "Source Directory";
        this.folderPath.TextAlign = System.Drawing.ContentAlignment.TopCenter;
        this.folderPath.UseVisualStyleBackColor = true;
        this.folderPath.Click += new System.EventHandler(this.sourceFiles_Click);
        // 
        // label1
        // 
        this.label1.AutoSize = true;
        this.label1.Location = new System.Drawing.Point(12, 94);
        this.label1.Name = "label1";
        this.label1.Size = new System.Drawing.Size(130, 13);
        this.label1.TabIndex = 3;
        this.label1.Text = "Choose the Target Folder:";
        // 
        // targetPath
        // 
        this.targetPath.Location = new System.Drawing.Point(12, 110);
        this.targetPath.Name = "targetPath";
        this.targetPath.Size = new System.Drawing.Size(114, 23);
        this.targetPath.TabIndex = 3;
        this.targetPath.Text = "Target Directory";
        this.targetPath.TextAlign = System.Drawing.ContentAlignment.TopCenter;
        this.targetPath.UseVisualStyleBackColor = true;
        this.targetPath.Click += new System.EventHandler(this.targetFolderPath_Click);
        // 
        // targetFolderBrowserDialog
        // 
        this.targetFolderBrowserDialog.Description = "targetFolderBrowserDialog";
        // 
        // label3
        // 
        this.label3.AutoSize = true;
        this.label3.Location = new System.Drawing.Point(12, 43);
        this.label3.Name = "label3";
        this.label3.Size = new System.Drawing.Size(133, 13);
        this.label3.TabIndex = 6;
        this.label3.Text = "Choose the Source Folder:";
        this.label3.Click += new System.EventHandler(this.sourceFolderPath_Click);
        // 
        // textBoxSourceDir
        // 
        this.textBoxSourceDir.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Left)
                    | System.Windows.Forms.AnchorStyles.Right)));
        this.textBoxSourceDir.Location = new System.Drawing.Point(135, 59);
        this.textBoxSourceDir.Name = "textBoxSourceDir";
        this.textBoxSourceDir.Size = new System.Drawing.Size(395, 20);
        this.textBoxSourceDir.TabIndex = 2;
        this.textBoxSourceDir.TextChanged += new System.EventHandler(this.textBoxSourceDir_TextChanged);
        // 
        // textBoxTargetDir
        // 
        this.textBoxTargetDir.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Left)
                    | System.Windows.Forms.AnchorStyles.Right)));
        this.textBoxTargetDir.Location = new System.Drawing.Point(135, 110);
        this.textBoxTargetDir.Name = "textBoxTargetDir";
        this.textBoxTargetDir.Size = new System.Drawing.Size(395, 20);
        this.textBoxTargetDir.TabIndex = 4;
        this.textBoxTargetDir.TextChanged += new System.EventHandler(this.textBoxTargetDirectory_TextChanged);
        // 
        // button_SaveSearch
        // 
        this.button_SaveSearch.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Right)));
        this.button_SaveSearch.Font = new System.Drawing.Font("Microsoft Sans Serif", 8.25F);
        this.button_SaveSearch.Location = new System.Drawing.Point(361, 177);
        this.button_SaveSearch.Name = "button_SaveSearch";
        this.button_SaveSearch.Size = new System.Drawing.Size(151, 23);
        this.button_SaveSearch.TabIndex = 12;
        this.button_SaveSearch.Text = "Save Search";
        this.button_SaveSearch.TextAlign = System.Drawing.ContentAlignment.TopCenter;
        this.button_SaveSearch.UseVisualStyleBackColor = true;
        this.button_SaveSearch.Click += new System.EventHandler(this.button_SaveSearch_Click);
        // 
        // groupBox2
        // 
        this.groupBox2.Anchor = ((System.Windows.Forms.AnchorSty开发者_StackOverflowles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)
                    | System.Windows.Forms.AnchorStyles.Left)
                    | System.Windows.Forms.AnchorStyles.Right)));
        this.groupBox2.Location = new System.Drawing.Point(15, 206);
        this.groupBox2.Name = "groupBox2";
        this.groupBox2.Size = new System.Drawing.Size(762, 206);
        this.groupBox2.TabIndex = 20;
        this.groupBox2.TabStop = false;
        this.groupBox2.Text = "Logging Window";
        this.groupBox2.Enter += new System.EventHandler(this.groupBox2_Enter);
        // 
        // buttonClearLog
        // 
        this.buttonClearLog.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Right)));
        this.buttonClearLog.Location = new System.Drawing.Point(361, 148);
        this.buttonClearLog.Name = "buttonClearLog";
        this.buttonClearLog.Size = new System.Drawing.Size(151, 23);
        this.buttonClearLog.TabIndex = 13;
        this.buttonClearLog.Text = "Clear Log";
        this.buttonClearLog.TextAlign = System.Drawing.ContentAlignment.TopCenter;
        this.buttonClearLog.UseVisualStyleBackColor = true;
        // this.buttonClearLog.Click += new System.EventHandler(this.buttonClearLog_Click);
        // 
        // buttonCancelSearch
        // 
        this.buttonCancelSearch.Location = new System.Drawing.Point(135, 148);
        this.buttonCancelSearch.Name = "buttonCancelSearch";
        this.buttonCancelSearch.Size = new System.Drawing.Size(111, 23);
        this.buttonCancelSearch.TabIndex = 21;
        this.buttonCancelSearch.Text = "Cancel Search";
        this.buttonCancelSearch.TextAlign = System.Drawing.ContentAlignment.TopCenter;
        this.buttonCancelSearch.UseVisualStyleBackColor = true;
        // this.buttonCancelSearch.Click += new System.EventHandler(this.buttonCancelSearch_Click);
        // 
        // sourceFileOpenFileDialog
        // 
        this.sourceFileOpenFileDialog.DefaultExt = "xlsx";
        this.sourceFileOpenFileDialog.InitialDirectory = "I:\\CommissisionReconciliation\\Review\\";
        // 
        // sourceFolderBrowserDialog
        // 
        // this.sourceFolderBrowserDialog.HelpRequest += new System.EventHandler(this.folderBrowserDialog1_HelpRequest);
        // 
        // textBoxSourceFiles
        // 
        this.textBoxSourceFiles.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Left)
                    | System.Windows.Forms.AnchorStyles.Right)));
        this.textBoxSourceFiles.Location = new System.Drawing.Point(135, 12);
        this.textBoxSourceFiles.Name = "textBoxSourceFiles";
        this.textBoxSourceFiles.Size = new System.Drawing.Size(395, 20);
        this.textBoxSourceFiles.TabIndex = 22;
        this.textBoxSourceFiles.TextChanged += new System.EventHandler(this.textBoxSourceFiles_TextChanged);
        // 
        // sourceFiles
        // 
        this.sourceFiles.Location = new System.Drawing.Point(12, 12);
        this.sourceFiles.Name = "sourceFiles";
        this.sourceFiles.Size = new System.Drawing.Size(117, 23);
        this.sourceFiles.TabIndex = 23;
        this.sourceFiles.Text = "Select Files";
        this.sourceFiles.TextAlign = System.Drawing.ContentAlignment.TopCenter;
        this.sourceFiles.UseVisualStyleBackColor = true;
        this.sourceFiles.Click += new System.EventHandler(this.sourceFiles_Click_1);
        // 
        // MainForm
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(841, 424);
        this.Controls.Add(this.sourceFiles);
        this.Controls.Add(this.textBoxSourceFiles);
        this.Controls.Add(this.buttonCancelSearch);
        this.Controls.Add(this.buttonClearLog);
        this.Controls.Add(this.button_SaveSearch);
        this.Controls.Add(this.textBoxTargetDir);
        this.Controls.Add(this.textBoxSourceDir);
        this.Controls.Add(this.label3);
        this.Controls.Add(this.targetPath);
        this.Controls.Add(this.label1);
        this.Controls.Add(this.folderPath);
        this.Controls.Add(this.button_Execute);
        this.Controls.Add(this.listBox1);
        this.Controls.Add(this.groupBox2);
        this.MinimumSize = new System.Drawing.Size(857, 361);
        this.Name = "MainForm";
        this.Text = "CCP Commission File Consolidation Process Utility v1.0.0";
        // this.Load += new System.EventHandler(this.Form1_Load);
        this.ResumeLayout(false);
        this.PerformLayout();

    }

    #endregion

    private System.Windows.Forms.Button button_Execute;
    private System.Windows.Forms.ListBox listBox1;
    private System.Windows.Forms.Button folderPath;
    private System.Windows.Forms.Label label1;
    private System.Windows.Forms.Button targetPath;
    private System.Windows.Forms.FolderBrowserDialog targetFolderBrowserDialog;
    private System.Windows.Forms.Label label3;
    private System.Windows.Forms.TextBox textBoxSourceDir;
    private System.Windows.Forms.TextBox textBoxTargetDir;
    private System.Windows.Forms.Button button_SaveSearch;
    private System.Windows.Forms.GroupBox groupBox2;
    private System.Windows.Forms.Button buttonClearLog;
    private System.Windows.Forms.Button buttonCancelSearch;
    private System.Windows.Forms.OpenFileDialog sourceFileOpenFileDialog;
    private System.Windows.Forms.FolderBrowserDialog sourceFolderBrowserDialog;
    private System.Windows.Forms.TextBox textBoxSourceFiles;
    private System.Windows.Forms.Button sourceFiles;
    }
 }

Try closing the solution, re-opening it and then opening the form. In my experience, the error may go away, only to re-surface again later.

If the error doesn't go away, then according to
http://connect.microsoft.com/VisualStudio/feedback/details/497218/the-class-name-is-not-a-valid-identifier-for-this-language-can-reproduce-w-vs-2008
and
http://social.msdn.microsoft.com/Forums/en/winformsdesigner/thread/f2c1a027-3e49-4f7f-a4c2-c91a8fde25fc
you may have too many closing brackets somewhere.

I had this error, and it was because i had an invalid variable name (started with a number). Hope this helps anyone else how may run into this issue.

Try closing the solution,clean the solution and rebuild the solution and them proble will go,main form designer will be visible...

and if still is there..just go n check the last modification u done in code..over there you may have too many closing brackets.

hope this will work for you..

In my case I had added a text file that and the default build action was content. When I changed that to build action none then the error "The class name '?' is not a valid identifier for this language." went away.

The usual approach is to look for errors in the Design code but I discovered that this is unhelpful because everything is correct there (the Designer generated good code and I hadn't touched it).

The error turned out to be in my own code (a try was missing curly braces). It's interesting that an error in my code broke the Designer. I expected it to be independent (to a certain extend).