Decred mining yields all rejects:
********** cpuminer-opt 3.6.10 ***********
A CPU miner with multi algo support and optimized for CPUs
with AES_NI and AVX extensions.
BTC donation address: 12tdvfF7KmAsihBXQXynT6E6th2c2pByTT
Forked from TPruvot's cpuminer-multi with credits
to Lucas Jones, elmad, palmd, djm34, pooler, ig0tik3d,
Wolf0, Jeff Garzik and Optiminer.
CPU: Intel(R) Xeon(R) CPU X5660 @ 2.80GHz
CPU features: SSE2
SW built on Oct 12 2017 with GCC 4.8.3
SW features: SSE2
Algo features: SSE2
Start mining with SSE2
[2017-10-16 18:29:04] Starting Stratum on stratum+tcp://decred.mine.zpool.ca:574
4
[2017-10-16 18:29:04] 18 miner threads started, using 'decred' algorithm.
[2017-10-16 18:29:05] Stratum difficulty set to 0.1
[2017-10-16 18:29:09] Rejected 1/1 (100.0%), 71.70 MH, 29.45 MH/s
[2017-10-16 18:29:09] reject reason: Invalid share
[2017-10-16 18:29:23] Rejected 2/2 (100.0%), 111.53 MH, 29.87 MH/s
[2017-10-16 18:29:23] reject reason: Invalid share
[2017-10-16 18:29:25] Rejected 3/3 (100.0%), 156.91 MH, 30.16 MH/s
[2017-10-16 18:29:25] reject reason: Invalid share
[2017-10-16 18:29:41] Rejected 4/4 (100.0%), 159.94 MH, 30.16 MH/s
[2017-10-16 18:29:41] reject reason: Invalid share
[2017-10-16 18:29:46] Rejected 5/5 (100.0%), 260.77 MH, 30.42 MH/s
[2017-10-16 18:29:46] reject reason: Invalid share
I tried old v3.4.12 with same result. Possibly a change in algo? I recall it used to work on zpool.
Same result obtained with a more recent CPU:
********** cpuminer-opt 3.6.10 ***********
A CPU miner with multi algo support and optimized for CPUs
with AES_NI and AVX extensions.
BTC donation address: 12tdvfF7KmAsihBXQXynT6E6th2c2pByTT
Forked from TPruvot's cpuminer-multi with credits
to Lucas Jones, elmad, palmd, djm34, pooler, ig0tik3d,
Wolf0, Jeff Garzik and Optiminer.
CPU: Intel(R) Core(TM) i7-6600U CPU @ 2.60GHz
CPU features: SSE2 AES AVX AVX2
SW built on Oct 12 2017 with GCC 4.8.3
SW features: SSE2 AES AVX AVX2
Algo features: SSE2
Start mining with SSE2
[2017-10-16 18:34:01] 2 miner threads started, using 'decred' algorithm.
[2017-10-16 18:34:01] Starting Stratum on stratum+tcp://decred.mine.zpool.ca:5744
[2017-10-16 18:34:02] Stratum difficulty set to 0.001
[2017-10-16 18:34:04] Rejected 1/1 (100.0%), 2924.23 kH, 2398.81 kH/s
[2017-10-16 18:34:04] reject reason: Invalid share
[2017-10-16 18:34:05] Rejected 2/2 (100.0%), 4567.93 kH, 6083.48 kH/s
[2017-10-16 18:34:05] reject reason: Invalid share
[2017-10-16 18:34:05] Rejected 3/3 (100.0%), 4567.93 kH, 6083.48 kH/s
[2017-10-16 18:34:05] reject reason: Invalid share
[2017-10-16 18:34:06] Rejected 4/4 (100.0%), 9594.73 kH, 5915.19 kH/s
[2017-10-16 18:34:06] reject reason: Invalid share
[2017-10-16 18:34:07] Rejected 5/5 (100.0%), 14.82 MH, 6528.50 kH/s
[2017-10-16 18:34:07] reject reason: Invalid share
[2017-10-16 18:34:09] Rejected 6/6 (100.0%), 17.47 MH, 6483.22 kH/s
[2017-10-16 18:34:12] reject reason: Invalid share