Local ubuntu16.04 compiles btcpool source code, and after completion, there is an error running its test program simulator

1. Run the sserver program first

cd /work/btcpool/build/run_sserver
./sserver -c sserver.cfg -l log_sserver/

2. Run simulator

cd /work/btcpool/build/run_simulator
./simulator -c simulator.cfg -l log_simulator/

3. Simulated mining machine connection, error:

minerd -o stratum+tcp://127.0.0.1:3333 -O aaa:1

[2018-04-04 15:17:06] Binding thread 0 to cpu 0
[2018-04-04 15:17:06] Binding thread 1 to cpu 1
[2018-04-04 15:17:06] Starting Stratum on stratum+tcp://127.0.0.1:3333
[2018-04-04 15:17:06] 4 miner threads started, using "scrypt" algorithm.
[2018-04-04 15:17:06] Binding thread 2 to cpu 2
[2018-04-04 15:17:06] Binding thread 3 to cpu 3
[2018-04-04 15:17:07] JSON-RPC call failed: [
   27,
   "Illegal params",
   null
]
[2018-04-04 15:17:07] ...retry after 30 seconds

is there an error in json-RPC here because there are other dependent services that have not been started? What kind of service is it?

the log of sserver is as follows

root@zc-x0:/work/btcpool/build-sharp tail -f run_sserver/log_sserver/sserver.INFO 
I0408 09:35:59.537277  9953 StratumSession.cc:246] client connect, ip: 127.0.0.1
I0408 09:35:59.538455  9953 StratumServer.cc:1136] socket closed
I0408 09:36:29.539168  9953 StratumSession.cc:246] client connect, ip: 127.0.0.1
I0408 09:36:29.540217  9953 StratumServer.cc:1136] socket closed
I0408 09:36:59.540978  9953 StratumSession.cc:246] client connect, ip: 127.0.0.1
I0408 09:36:59.542340  9953 StratumServer.cc:1136] socket closed
I0408 09:37:29.543114  9953 StratumSession.cc:246] client connect, ip: 127.0.0.1
I0408 09:37:29.544587  9953 StratumServer.cc:1136] socket closed

simulator log is as follows

root@zc-x0:/work/btcpool/build-sharp tail -f run_simulator/log_simulator/simulator.INFO 
E0408 09:07:11.401319 25623 StratumClient.cc:144] json result is null, err: 1
E0408 09:07:11.652422 25623 StratumClient.cc:144] json result is null, err: 1
E0408 09:07:11.652513 25623 StratumClient.cc:144] json result is null, err: 1
E0408 09:07:11.652572 25623 StratumClient.cc:144] json result is null, err: 1
E0408 09:07:11.652631 25623 StratumClient.cc:144] json result is null, err: 1
E0408 09:07:11.652688 25623 StratumClient.cc:144] json result is null, err: 1