I've installed UmbracoFileSystemProviders.Azure ver. 0.5.10 through NuGet, and changed FileSystemProviders.config to this

<Provider alias="media" type="Our.Umbraco.FileSystemProviders.Azure.AzureBlobFileSystem, Our.Umbraco.FileSystemProviders.Azure">
<Parameters>
  <add key="containerName" value="media" />
  <add key="rootUrl" value="https://mystorage.blob.core.windows.net/" />
  <add key="connectionString" value="DefaultEndpointsProtocol=https;AccountName=mystorage;AccountKey=password;EndpointSuffix=core.windows.net"/>
  <!--Optional configuration value determining the maximum number of days to cache items in the browser. Defaults to 365 days. -->
  <add key="maxDays" value="365" />
</Parameters>

When i build and run my site i get this error message

(Gotta love the Danish error messages) I think the error message translates to

Exception has been thrown by the target of an invocation.

Any ideas why this error suddenly pops up?