Unable to upgrade tot ios9 because The software for iphone was corrupted during download

Hi,

Since ios9 is out I try to update my iphone 5s from ios 8.4.1 to ios9.

Everytime I got the message "The software for iphone was corrupted during download".

I tried to upgrade on my IPhone and using ITunes on my PC (windows 10).

On my PC I always get a message before the update starts that there are paid items on my phone which are not transfered to my PC. Even after I synchronized and made a backup.

I had an issue with an album I bought from itunes on my iphone which I lost. I was also not able to download it again from itunes. This was possible again after the helpdesk put it back for me again. Maybe there are still parts of the first download left behind and cause this.

Does anyone has a suggestion what I can do to solve this?

Thanks,

john