I’m using the samsung J1 core and there was an error just like the one you are describing. So I downloaded the latest smart switch software but doesn’t seem to detect my phone. So I downloaded a previous version of smart switch software. It detected my device but then it wasn’t able to fix the error. A new error message pops up saying it doesn’t support my device. Now i’m trying to download the firmware and install it on my phone using Odin software. The firmware file size is around 772 MB. You can check out the steps at Hocview