Uploading issue while create a blank app

error message :SharpSvn.SvnSerfException: Error running context: The server unexpectedly closed the connection.    at SharpSvn.SvnClientArgs.HandleResult(SvnClientContext client, SvnException error, Object targets) in d:\bb\sharpsvn-v1.900x\v40\src\sharpsvn\svnclientargs.cpp:line 78    at SharpSvn.SvnClient.CheckOut(SvnUriTarget url, String path, SvnCheckOutArgs args, SvnUpdateResult& result) in d:\bb\sharpsvn-v1.900x\v40\src\sharpsvn\commands\checkout.cpp:line 62    at SharpSvn.SvnClient.CheckOut(SvnUriTarget url, String path) in d:\bb\sharpsvn-v1.900x\v40\src\sharpsvn\commands\checkout.cpp:line 35    at Mendix.Modeler.VersionControl.SvnConnector.Checkout(IRemoteRepository remoteRepository, IRevLine branchToCheckout, String targetProjectDirectory) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.VersionControl.Windows\Svn\SvnConnector.cs:line 91
1 answers

I have seen this error and sometimes it goes away after sometime if you try again. Maybe this is due to some network connection issue. Check your connectivity or just try again. 
Other than this, sometimes Mendix services are down which you can check at https://status.mendix.com/
Right now everything is up and operational.

There could be some other reasons linked to repository size but in your case the app is blank, so I guess it should work if you try again some steps like Reconnect your network. Restart studio pro etc.