Chances are you have had this happen to you.

You start getting compile errors on your asp.net controls in your code behind pages.  But the controls exist on the page??  Whats the deal?

Well, in VS2003 the designer would create the class level controls in your code behind.  It would created a special region where it would put all it’s autogenerated code.

2005 brought the new “Web Site Project” which used a “CodeFile” instead of “CodeBehind” attribute on the page tag.  In addition, the codefile/codebehind became a Partial Class.  VS would then put all the generated code in a seperate file so it didn’t cramp up your code behind.

In Web Application projects, the autogen code is stored in .designer.vb files:

But everynow and then, things get out of sync, or the designer files get totally lost.

Here is how you can regenerate them:

First, make sure your class names, and page attributes are right.  The Page tag should have a Codebeind attribute pointing to the aspx.vb file and an Inherits attribute that contains the fully qualified class name in the codebehind.  (This instructions are for Web App Projects, not Web Site Projects, which use Codefile instead of Codebehind).

Second, create a designer file if one doesn’t exist.  Click the “Show all files” icon in the Solution Explorer to see if you have designer files.  If not, add a class file with the right name page_name.aspx.designer.vb.  VS will automatically put it “under” the aspx page.

Make sure all namespaces are right.  Check your code beind, your designer file, and your page codebehind attribute.

Open your page in a designer and rename one of your controls.  Save everything and close the code and designer windows.  Open the designer back up and rename the control back.  Now look at your designer file, it should have a punch of controls in it, and now VS shouldn’t complain about compile errors in your code behind.