Error reading package

System.AggregateException: One or more errors occurred. (Package format doesn't support quick access) (The given header was not found.)
 ---> System.Exception: Package format doesn't support quick access
   at Relativity.APIReference.PackageData.ReadEntriesAsync(HttpClient client, String file) in C:\Dev\Relativity.APIReference\Data\PackageData.cs:line 245
   at Relativity.APIReference.PackageData.ReadAsync(HttpClient httpClient, String packageUri) in C:\Dev\Relativity.APIReference\Data\PackageData.cs:line 303
   at Relativity.APIReference.PackageData.PackageDataCache.ReadPackageFromUrl(PackageData package, HttpClient httpClient, CancellationToken token) in C:\Dev\Relativity.APIReference\Data\PackageData.cs:line 602
   at Relativity.APIReference.PackageData.PackageDataCache.GetValueAsync(String arg0, PackageVersion arg1, HttpClient httpClient, CancellationToken token) in C:\Dev\Relativity.APIReference\Data\PackageData.cs:line 578
   --- End of inner exception stack trace ---
 ---> (Inner Exception #1) System.InvalidOperationException: The given header was not found.
   at System.Net.Http.Headers.HttpHeaders.GetValues(HeaderDescriptor descriptor)
   at Relativity.APIReference.PackageData.ReadEntriesAsync(HttpClient client, String file) in C:\Dev\Relativity.APIReference\Data\PackageData.cs:line 0
   at Relativity.APIReference.PackageData.ReadAsync(HttpClient httpClient, String packageUri) in C:\Dev\Relativity.APIReference\Data\PackageData.cs:line 303
   at Relativity.APIReference.PackageData.PackageDataCache.ReadPackageFromUrl(PackageData package, HttpClient httpClient, CancellationToken token) in C:\Dev\Relativity.APIReference\Data\PackageData.cs:line 602
   at Relativity.APIReference.PackageData.PackageDataCache.GetValueAsync(String arg0, PackageVersion arg1, HttpClient httpClient, CancellationToken token) in C:\Dev\Relativity.APIReference\Data\PackageData.cs:line 578<---