hope someone can help. I use an Antminer U3 on a Raspberry Pi with Minera and CGminer.

When I mine everything with Scrypt-Algo, I get 100% rejected shares. My current pool is ghash.io.

My log looks like:

Rejected 09ffd3f1 Diff 26/16 AU3 0 pool 1 (Low difficulty share)

my config file:

    "api-listen": true,
    "api-allow": "W:",
    "log-file": "\/var\/log\/minera\/cgminer.log",
    "scrypt": true,
    "scan": "all",
    "pools": [
            "url": "stratum+tcp://multi.ghash.io:3333",
            "user": "WORKER",
            "pass": "123"

My additional options are: --au3-volt 780 --au3-freq 238

Minera shows a hashrate of about 60 GH/s, Ghash.io shows about 1MH/s in the multipool.

When i change to the bitcoin pool, everything works fine.

Any ideas? Could it be affected by the pool difficulty, i can set on the ghash.io panel?

Thanks in advance

  • 2
    Isn't the Antminer U3 an SHA256 ASIC miner? How are you expecting it to mine using scrypt? Aug 24, 2015 at 2:20
  • Yep. The Antminer is a Bitcoin miner. Aug 25, 2015 at 5:18

1 Answer 1


An Antminer U3 is a SHA256 miner, it can not mine anything else. The shares are being rejected because they are effectively nonsense to the receiving pool, as they do not satisfy the difficulty requirements they have asked for.

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