There is a known issue with the current SDK installer caused by corruption of temporary files. Fortunately, the issue is quite rare and – so far – it has only affected a small number of users. We’re now looking into a long term fix. In the meantime, the instructions below can be followed to work around the problem:
Navigate to your Operating System’s temporary directory (usually ‘C:Users[USER]AppDataLocalTemp’ on Windows, ‘/tmp’ on OS X and Linux)
If they exist, delete the .bitrock folder and PAK files in this location
Run the installer again
If you’re still experiencing issues on Windows, we would recommend cleaning the entire %temp% directory. This can be done safely with the Windows Disk Cleanup tool’s “Temporary files” option.