Result 17 (0x11) means it’s a data-out-of-bound error:
https://github.com/OpenSprinkler/OpenSprinkler-Firmware/blob/master/server.cpp#L100
Really the only thing I can think of would be if you have reached the maximum number of programs. You said you have 8 programs, which should be within the maximum (17 for firmware 2.1.7). Can you export your configurations to a file and attach it here (you may want to mask out sensitive information), or you can send it as attachment to a support ticket.