I have WAP project in VS 2005 SP1 (with WAP included) . One of my ascx files, when open as "View Markup"(aka Source tab) shows error

 ASP.NET runtime error: There is no build provider registered for the extension ''. You can register one in the <compilation><buildProviders> section in machine.config or web.config. Make sure is has a BuildProviderAppliesToAttribute attribute which includes the value 'Web' or 'All'.  I found at least one other had the same problem.
If I switch to Designer Tab, the error disappeared.
The error doesn't stop the compile or run, just annoyying tosee it in error list.

Any ideas, what it can be caused by?

I am also seeing this error.

In this case it was a WAP that was created pre-SP 1 and then brought into a new VS 2005 SP1 install on a different computer. The same project also now has issues with user controls and controls registered in the web.config. Ugh.

I should add I am also using Resharper 2.5, but the VS install is otherwise pristine (and never used before this).

 

Update II: things started breaking to the point it became worth it to rebuild the project. That is, to delete the Web Application project, create a new one and re-add all the files and relink in the libraries. Good news is that seems to fix things. In any case, it appears to be an issue with pre-SP1 Web Application projects under SP1.

 

In my case copying the following piece of code that was in the machine web.config (C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727) to the project web.config solved the problem:

<buildProviders>
        <add extension=".aspx" type="System.Web.Compilation.PageBuildProvider" />
        <add extension=".ascx" type="System.Web.Compilation.UserControlBuildProvider" />
        <add extension=".master" type="System.Web.Compilation.MasterPageBuildProvider" />
        <add extension=".asmx" type="System.Web.Compilation.WebServiceBuildProvider" />
        <add extension=".ashx" type="System.Web.Compilation.WebHandlerBuildProvider" />
        <add extension=".soap" type="System.Web.Compilation.WebServiceBuildProvider" />
        <add extension=".resx" type="System.Web.Compilation.ResXBuildProvider" />
        <add extension=".resources" type="System.Web.Compilation.ResourcesBuildProvider" />
        <add extension=".wsdl" type="System.Web.Compilation.WsdlBuildProvider" />
        <add extension=".xsd" type="System.Web.Compilation.XsdBuildProvider" />
        <add extension=".js" type="System.Web.Compilation.ForceCopyBuildProvider" />
        <add extension=".lic" type="System.Web.Compilation.IgnoreFileBuildProvider" />
        <add extension=".licx" type="System.Web.Compilation.IgnoreFileBuildProvider" />
        <add extension=".exclude" type="System.Web.Compilation.IgnoreFileBuildProvider" />
        <add extension=".refresh" type="System.Web.Compilation.IgnoreFileBuildProvider" />
        <add extension=".svc" type="System.ServiceModel.Activation.ServiceBuildProvider, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
        <add extension=".asp" type="System.Web.Compilation.PageBuildProvider" />
      </buildProviders>
      <expressionBuilders>
        <add expressionPrefix="Resources" type="System.Web.Compilation.ResourceExpressionBuilder" />
        <add expressionPrefix="ConnectionStrings" type="System.Web.Compilation.ConnectionStringsExpressionBuilder" />
        <add expressionPrefix="AppSettings" type="System.Web.Compilation.AppSettingsExpressionBuilder" />
      </expressionBuilders>