A VDMA Decode Error occurs when the address request is targeted to an address that does not exist. As an example, the valid base address offset for DDR might be assigned in IP integrator, generally defaulting to 0x80000000. If START_ADDRESS (1 to n) is set to values outside of the range of addresses for the DDR (or other connected slave), this error will occur because the AXI Interconnect will not be able to decode the address to a valid slave.