The most common errors encountered when getting started with SDR come from libusb. This is the low-level library used to communicate with the device.

Error codes may look something like this:

IOError: Error code -1 when opening SDR (device index = 0)

These usually indicate an issue with the installation of librtldsr or with user permissions. Troubleshooting at this point is much easier with the built-in test utilities included in librtldsr, namely rtl_test

The error codes are described here: http://libusb.sourceforge.net/api-1.0/group__libusb__misc.html