I started co-mining on Slush's pool successfully for about 48 hours, but from there on I haven't been able to connect to it again. It logs in the console this, no matter if I'm using a valid worker and password or not:

2013-05-26 12:55:19: Listener for "Default" started
2013-05-26 12:55:20: Listener for "Default": api2.bitcoin.cz:8332 26/05/2013 12:55:20, checking for stratum...
2013-05-26 12:55:20: Listener for "Default": api2.bitcoin.cz:8332 26/05/2013 12:55:20, started OpenCL miner on platform 0, device 0 (Turks)
2013-05-26 12:55:20: Listener for "Default": api2.bitcoin.cz:8332 26/05/2013 12:55:20, no response to getwork, using as stratum
2013-05-26 12:55:20: Listener for "Default": api2.bitcoin.cz:8332 26/05/2013 12:55:20,  No JSON object could be decoded
2013-05-26 12:55:30: Listener for "Default": api2.bitcoin.cz:8332 26/05/2013 12:55:30, Failed to subscribe
2013-05-26 12:55:32: Listener for "Default": api2.bitcoin.cz:8332 26/05/2013 12:55:32, IO errors - 1, tolerance 2
2013-05-26 12:55:33: Listener for "Default" shutting down

Of course, I've checked my connection, and I've started GUIMiner with administrator privileges. I'm using Windows 7.


The problem is that in GUIMiner, the URL for Slush's pool is:


That address has been deprecated, and it falls back to the GetWork protocol. From Slush's Pool news:

Default mining URL for Stratum is stratum.bitcoin.cz:3333. If you're still using api.bitcoin.cz, please fix your URL to prevent fallback to deprecated Getwork protocol.

In the GUIMiner interface, instead of choosing "Slush's Pool" from the dropdown menu, choose "other" and then enter




  • Nice, it worked! – j4nSolo May 26 '13 at 21:37
  • 2
    Thank you this was verry helpfull, stratum.bitcoin.cz:3333 worked for me. – user5544 Jun 13 '13 at 2:00
  • i had the exact same problem but following ur instructions didnt help me a bit. whats wrong? – user5567 Jun 14 '13 at 9:00
  • When I tried it with the CPU miner (not GPU), api.bitcoin.cz:8332 worked, but stratum.bitcoin.cz:3333 did not work. – Peter Mortensen Jan 5 '14 at 18:11

Use stratum.bitcoin.cz and port 3333 in GUIMiner, not like http://stratum.bitcoin.cz:3333 that was mensioned in another answer.

protected by Community Nov 19 '13 at 10:32

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