Nothing on Google or SO relates to this specific problem, so asking a new question. I created a brand new Asp.Net MVC *Web Application* with the standard *user-security* option. I also created an empty database in Azure.

I did nothing but change the default connection string to this:

```
  <connectionStrings>
    <add name="DefaultConnection" 
         connectionString="data source=mydatabase.database.windows.net;initial catalog=Feedback;persist security info=True;user id=LeaveFeedbackuser;password=mypassword;MultipleActiveResultSets=True;App=EntityFramework"
         providerName="System.Data.SqlClient" />
  </connectionStrings>

```

and the default connection factory to this:

```
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="v12.0" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>

```

On attempting to register (when I would expect it to normally create the `AspNetUsers` and related tables) I get the following error:

> 
> The magic number in GZip header is not correct. Make sure you are
>  passing in a GZip stream. Description: An unhandled exception
>  occurred during the execution of the current web request. Please
>  review the stack trace for more information about the error and where
>  it originated in the code. 
> 
> 
> Exception Details: System.IO.InvalidDataException: The magic number
>  in GZip header is not correct. Make sure you are passing in a GZip
>  stream.
> 
> 
> Source Error: 
> 
> 
> Line 153: { Line 154: var user = new
>  ApplicationUser { UserName = model.Email, Email = model.Email }; Line
>  155: var result = await UserManager.CreateAsync(user,
>  model.Password); Line 156: if (result.Succeeded) Line
>  157: {
> 
> 
> 

What has any of this to do with GZip and what is causing this error? This has stopped me getting OWIN working with my Azure database for several days now.