Question: I am having an issue with an existing site that was functioning until last week. When I open the site in VS 2013 I get a "Object reference not set to an instance of an object" error/warning on the page declaration of the `.aspx` pages and `.master` pages. The website builds correctly but when run only displays a blank page and no errors.

I have verified that the code behind file exists and it's namespace and class are properly entered into the page declaration. Adding a new page to the project gets the same error and I have verified the references are all present. The website is with 3.5 framework. Any help would be appreciated. Thanks.

Clayton

![Image of error message](https://i.stack.imgur.com/Qsz3B.png)

Answer: 
Since I wasn't making any headway in getting this resolved I decided to create a new web project and move all the existing files into the new project. I decided to do this one file at a time to see if I could nail down the page or setting causing the issue. All the files copied over and the site ran as expected until I started to tweek the web config file to match some of the settings from the old project. Everything worked until I added the line

```
<identity impersonate="true" userName="domain\Username" password="Password" />

```

Once I saved and ran the webpage I started getting the same errors from the other project. Commenting out this line resolved the issue for me but now I've got to figure out why that would cause such a strange issue.

Thanks everyone for their time.

Edit: Oddly enough the line works without specifying the user account so if I put `<identity impersonate="true" />` then everything works as expected.
(it looks like you have done this already but) the only other thing i can see is that 'CodeBehind' usually matches 'Inherits'. it doesn't have to match but make sure that 'Inherits'

```
... Inherits="_default"

```

matches the code behind's partial class:

```
public partial class _default : System.Web.UI.Page

```

your page's 'Inherits' says **RenewTemplate.Default**. does that exactly match the code behind?