The most common mistake done by FPGA learners are they try to download Bit file using older version of Xilinx ISE Software to latest FPGA Family or vise versa.
There are many number of devices released by Xilinx from time to time.Such us,
sparatn-3, spartan-3e, Spartan-3an, Spartan-6, Virtex 2,4,5,6,7, Zync FPGA.
Spartan-3/3e FPGA device is only compatible with Xilinx 7 or above
Spartan-3an FPGA device is only compatible with Xilinx 9.2 or above
Spartan-6 device is compatible with Xilinx 11.4 or above.
Zync FPGA device is compatible with 13/14 version only.