I am updating a website for my project at work. It was a .Net 1.1 site converted to a .Net 2.0 site. We are adding some new user controls to the site. I implemented one of those controls on a new page and generated a runtime error like this:

"The base class includes the field 'WebUserControl1', but its type (common_WebUserControl) is not compatible with the type of control (ASP.common_webusercontrol_ascx)"

Hunting around with Google turned up several possibilities, but none helped until I found this link, http://forums.asp.net/t/960707.aspx. A post by ‘Maduka’ suggested changing the Codefile attribute of the page to CodeBehind. This worked in my case. It works the other way too. Change the control’s CodeBehind property to CodeFile.

Without digging deep, I would presume that CodeFile is the .Net 2.0+ code behind method, as this is the default value for the new user controls. So, in our implementation, we are changing pages that use the new controls to use the CodeFile attribute instead of CodeBehind. I am not sure which is best practice, but this is what works for me. Your mileage may vary.

And, it turns out I may have this backward. Reading the posts a bit more indicates that CodeBehind is the new model. I will need to look at this more closely. I am hoping to update the site to .Net 3.5 by the end of the year, and I would like to clean this stuff up.