Download bootloader fails at entry 472

I can’t download bootloader on RK3566. I added debug statements and I see the tool is able to write 471 entries and fails to write 472 entry.

The command I used is:

sudo rkdeveloptool db rk356x_spl_loader_ddr1056_v1.10.111.bin

Error is:

16:24:53 Error:RKU_DeviceRequest–>DeviceRequest vendor=0x472 failed, err=-1
16:24:53 <LAYER 20-1> ERROR:DownloadBoot–>Boot_VendorRequest472 failed,index(0)

Any ideas what could be going wrong?