title: The type or namespace name 'OwinStartupAttributeAttribute' could not be found
body: <p>I am compiling some code that I did not write.</p>
  
  <p>When I do Build -> Build Solution I get this error:</p>
  
  <pre><code>The type of namespace name 'OwinStartupAttributeAttribute' could not be found (are you missing a using directive or an assembly reference?)
  </code></pre>
  
  <p>On this line of code:</p>
  
  <pre><code>using Microsoft.Owin;
  using Owin;
  
  [assembly: OwinStartupAttribute(typeof(CCACustomerPayment.Startup))]    
  </code></pre>
  
  <p>So, I try to do this:</p>
  
  <pre><code>PM&gt; install-package microsoft.owin
  </code></pre>
  
  <p>And get this error:</p>
  
  <pre><code>Attempting to gather dependency information for package 'microsoft.owin.4.0.0' with respect to project 'CustomerPayment', targeting '.NETFramework,Version=v4.5'
  Gathering dependency information took 1.35 sec
  Attempting to resolve dependencies for package 'microsoft.owin.4.0.0' with DependencyBehavior 'Lowest'
  One or more unresolved package dependency constraints detected in the existing packages.config file. All dependency constraints must be resolved to add or update packages. If these packages are being updated this message may be ignored, if not the following error(s) may be blocking the current package operation: 'Microsoft.Owin.Host.SystemWeb 3.0.1 constraint: Owin (&gt;= 1.0.0)', 'Microsoft.Owin.Host.SystemWeb 3.0.1 constraint: Microsoft.Owin (&gt;= 3.0.1)', 'Microsoft.Owin.Security 3.0.1 constraint: Owin (&gt;= 1.0.0)', 'Microsoft.Owin.Security 3.0.1 constraint: Microsoft.Owin (&gt;= 3.0.1)', 'Microsoft.Owin.Security.Cookies 2.1.0 constraint: Owin (&gt;= 1.0.0)', 'Microsoft.Owin.Security.Cookies 2.1.0 constraint: Microsoft.Owin (&gt;= 2.1.0)', 'Microsoft.Owin.Security.OAuth 2.1.0 constraint: Owin (&gt;= 1.0.0)', 'Microsoft.Owin.Security.OAuth 2.1.0 constraint: Microsoft.Owin (&gt;= 2.1.0)'
  Resolving dependency information took 0 ms
  Resolving actions to install package 'microsoft.owin.4.0.0'
  Resolved actions to install package 'microsoft.owin.4.0.0'
  Retrieving package 'Microsoft.Owin 4.0.0' from 'nuget.org'.
  Retrieving package 'Owin 1.0.0' from 'nuget.org'.
  Adding package 'Owin.1.0.0' to folder 'C:\Users\ME\source\Customer\customerpayment\CustomerPayment\packages'
  Added package 'Owin.1.0.0' to folder 'C:\Users\Me\source\Customer\customerpayment\CustomerPayment\packages'
  Added package 'Owin.1.0.0' to 'packages.config'
  Successfully installed 'Owin 1.0.0' to CustomerPayment
  Install failed. Rolling back...
  Package 'Microsoft.Owin.4.0.0 : Owin [1.0.0, )' does not exist in project 'CustomerPayment'
  Removed package 'Owin.1.0.0' from 'packages.config'
  Package 'Microsoft.Owin.4.0.0 : Owin [1.0.0, )' does not exist in folder 'C:\Users\Me\source\ Customer\customerpayment\CustomerPayment\packages'
  Removing package 'Owin.1.0.0' from folder 'C:\Users\ME\source\Customer\customerpayment\CustomerPayment\packages'
  Removed package 'Owin.1.0.0' from folder 'C:\Users\ME\source\Customer\customerpayment\CustomerPayment\packages'
  Executing nuget actions took 529.79 ms
  install-package : Could not install package 'Microsoft.Owin 4.0.0'. You are trying to install this package into a project that targets '.NETFramework,Version=v4.5', but the package 
  does not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author.
  At line:1 char:1
  + install-package microsoft.owin
  + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      + CategoryInfo          : NotSpecified: (:) [Install-Package], Exception
      + FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PackageManagement.PowerShellCmdlets.InstallPackageCommand
  
  Time Elapsed: 00:00:01.9633227
  </code></pre>
  
  <p>I have also tried adding <code>--version 4.5</code> and other variations, but that does not work either.</p>
  
  <p>When I look at <code>Project -&gt; Add Reference</code> I do not see any option for Microsoft.owin.</p>
  
  <p>How do I get this code to compile?</p>