The designer cannot process unknown name 'mycomboBox_SourceType' at line 46

Question

I have a windows form where I have created my own custom comboBox code .cs class file in my project and used that in my form controls(designer files).

This works fine for the exsisting project where its been created.(i.e, I manually changed the code in designer file to get adapt to my custom control)

Problem: The same form and controls needs to be created in an another project(solution)...

When I copied mycombo.class file and the rest of the forms to the other project solution I get the below error (when tried opening my form designer file)....

"The designer cannot process unknown name 'comboBox_SourceType' at line 46. The code within the method 'InitializeComponent' is generated by the designer and should not be manually modified. Please remove any changes and try opening the designer again" 
Could not find type 'AP_CoSD_Tool.MyCombobox'. Please make sure that the assembly that contains this type is referenced. If this type is a part of your development project, make sure that the project has been successfully built using settings for your current platform or Any CPU. 

The project is working fine when running the file but when I open the desiner.cs file the error is occuring particularly for the custom combobox controls in the designer.cs files of all the forms copied.

Is there any soltuion for this issue ? Please let me know if any further information is required to solve this one....

The screenshot of the error is shown below :

when i click goto code it opens the respective designer file and goes to the below line:

this.tableLayoutPanel1.Controls.Add(this.comboBox_SourceType, 1, 0);
this.tableLayoutPanel1.Controls.Add(this.comboBox_commodity, 1, 3);
this.tableLayoutPanel1.Controls.Add(this.comboBox_BusinessType, 1, 1);
this.tableLayoutPanel1.Controls.Add(this.comboBox_group, 1, 2);

where comboBox_sourcetype and other comboboxes are the custom created controls.

Answer 1

I got this error trying to migrate older Designer-Generated Code to a Partial Class Designer for newer style. My fix was to make sure that I added any necessary imports to the top of the new class. It was throwing this error, but the underlying problem was a bit further up where a control wasn't fully qualified. Make sure your namespaces are included either inline or with an Import.