Bitmain Antminer Logs (Errors)

Logs	What does it mean	What to do
Chain[X]: find 0 asic or chain find 0 asic, will power off this chain	The board is not visible at all / not a single chip	1. Unplug the ASIC. 2. Pull out and firmly reinsert both thick power cables on this board. 3. Turn it on. → in 40–60% of cases, the S19kPro/XP/S21 will immediately find 126 chips and start working. Didn’t help. → the board needs repair.
Chain[X]: only find 47–90 asic	Half of the chips are missing	Reconnecting the power cables and ribbon cable. Didn’t help → board in for repair
autotune fail (especially on S21/S21+)	The board was unable to configure frequencies	1. Reconnect the cables 2. Factory Reset + fresh firmware 3. Didn’t help → 85% of the time the VRM (power supply on the board) is dead → board for repair
domain voltage abnormal / unstable	The voltage on the board dropped by 1.2 V	Take the board in for repair
CRC error (even 1–2 times per minute)	The chips don’t transmit data well to each other	This is the beginning of the end. In 1–4 weeks, the board will go to zero. Take it in for repairs.
nonce error	The chip counts as “garbage”	On older S9–S17, it’s a dead chip. On S19kPro and newer, 90% of the time it’s poor board power supply.
Temp[X]: 90–97 °C on S21	Normal for S21 in 2025	Do nothing, this is the normal state
Temp[X]: 95–100+ °C (any model)	Will pass out soon	Urgently improve airflow and remove dust
Fatal Error: some fan lost!	One fan does not spin or does not produce speed	Swap the fans → the error has moved → change the fan → the error remains at the same number → repair the controller
PSU error / voltage too low	The power supply is not working or there is a power failure in the socket	Remove the tees, check 220 V, try a different power supply
pic error / pic init fail	The small “brain” (PIC) on the board burned out	Board for repair
EEPROM error / eeprom checksum fail	The board’s memory has died or the data has been erased	90% of the time, the board needs repair. Reflashing the firmware rarely helps.

Launching the miner and software

Line in the log	What does it mean?	What to do
bmminer start / cgminer start	The main miner (the engine that calculates the hash) has started	Normal
restart bmminer	Restarting the miner within the system (without a full reboot of the ASIC)	See the lines above to see why it restarted
Found bmminer / start running bmminer	The controller has found and is running the miner binary	Normal
bmminer not running, restart…	The process has crashed, and the watchdog is trying to get it back up	Go up the log, looking for the reason for the drop (temperature, chips, power supply)

Definition of boards (Chain/Hashboard)

Line	What does it mean?	What to do
check_chain_num: chain_num = 3	ASIC is waiting for 3 hashboards (0, 1, 2)	Normal
chain[0] exist / chain[1] exist	The board was found by the cable	Normal
chain[2] is missing / chain[2] doesn’t exist	One of the boards is not responding at all	Check the board’s power supply, cables, and port; most likely, the board needs repair.
hashboard type: S19	The controller has identified the board type/model	Normal
hashboard missing	There is no board or it is “dead”	Check the cables and power supply. If that doesn’t help, take it in for repair.

ASIC detection for Bitmain

Line	What does it mean?	What to do
chain[0]: find 126 asic	126 chips found on board 0 – normal for S19 series	Everything is fine
chain[1]: find 0 asic	The board is physically present, but none of the chips are responding	Check the power supply and power cables (on the S19kPro/S19XP/S21 this is often a bad contact in the board’s power connector), and get it repaired if it still doesn’t detect the chips.
chain[1]: only find 47 asic	The board found some chips, the chain breaks	Check the cable; if it persists, repair the chain/chips.
chain[2]: asic detected = 76	Alternative format: 76 chips found	If it should be 76, it’s normal; if it’s more, it’s a defective chip and needs repair.
asic number is not enough	The number of chips found is below the norm	The board is defective and needs diagnostics.
chain 1 find asic 0, will power off this chain	The controller disables this board because no chips were found	The ASIC will work without this board, but the hashrate will drop; the board needs repairing.

Initialization of PIC, sensors and service controllers

Line	What does it mean?	What to do
pic init / init pic ok	The PIC controller has started successfully	Normal
pic error / failed to init pic	The power/sensor controller is not communicating	Most often, it’s a board repair; it can be fixed by reflashing the firmware, but not always
read temp sensor ok	Temperature sensors are responding	Normal
read temp sensor error / temp sensor read fail	Unable to read temperature from board	Check the cable; if it’s stable on one board, repair it.

Checking the fans at startup

Line	What does it mean?	What to do
check fan NUM: 2	Expected to have 2 fans (or 4 depending on the model)	Normal
Fan0 speed = 0, Fan1 speed = 0 (start phase)	At launch, the fans had not yet spun up	Normal if a normal value appears later
Fatal Error: some fan lost! (at the start)	Already at startup, the controller sees that one fan is not responding	Check the fan, cable, and connector; without fixing them, the ASIC won’t start mining.

Lines with calibration, autotune at startup

Line	What does it mean?	What to do
start autotune / begin tuning chain 0	Starting selection of frequencies and voltages for boards	Normal
tune chain 0 asic 0-125	All chips on the board are being configured	Normal
autotune fail (especially on the S21)	The board was unable to configure frequencies	Check the cables and reload the firmware. If that doesn’t help, the problem is in the VRM (power supply on the board itself) → send it for repair
calibration OK	Calibration completed successfully	Normal
calibration fail	Failed to calibrate the board	Restart; if it persists, repair

What can be seen in the logs — decoding

What can be seen in the logs	What does it mean	What to do
chain 1 lower hash	This board performs worse than the others, producing fewer terahashes	1. Compare the temperature of this board with others. 2. See how many chips it found at startup. 3. Are there any CRC errors? If so, the board is degrading.
only find 47 asic	The ASIC found fewer chips. The board is incomplete/partially dead.	The board is working, but it’s already broken. Diagnostics or repair is needed.
CRC error on chain 1	The chips on the board are transmitting data with errors. The chain is unstable.	If the CRCs are repeated, the board dies. You can mine temporarily, but the hashrate will drop, so send it in for repair.
disable chain 1	ASIC turned off the board itself — it was really bad	There’s nothing to be done. The ASIC will only mine on the remaining 1–2 boards. The board needs repairing.
asic X timeout / nonce error	One of the chips is glitching, responding poorly, or calculating incorrectly	A one-time error is normal. Frequent errors → the board degrades → repair.
hashrate is now much lower than avg	The hashrate is jumping, the ASIC is unstable	Check: 1) temperature; 2) whether one of the boards is working worse; 3) whether there is a CRC; 4) whether the ASIC is throttling due to heat.

Common power supply errors

What can be seen in the logs	What does it mean	What to do
voltage too low	The ASIC isn’t getting enough power. The voltage has dropped.	1. Measure the voltage in the outlet (should be 220–240V). 2. Remove extension cords/multiple power strips. 3. Check the power cable. 4. If the problem persists, replace the power supply.
voltage too high	Voltage above the norm is dangerous for the ASIC	Check the outlet with a multimeter. If the power supply indicates this, replace the power supply.
PSU error	The power supply is not working properly	1. Check the cable and contacts. 2. Replace the power supply — this is a clear sign it’s dying.
power lost	The power supply briefly disappeared/failed	1. Check the socket and cable. 2. Check the circuit breaker/panel. 3. If everything is ok, replace the power supply.
power low, reboot	The ASIC reboots due to a power supply drop	Check the power supply, replace the power supply.

Internal power supply of boards (domain voltage)

What can be seen in the logs	What does it mean	What to do
domain voltage abnormal	The voltage on one of the boards fluctuates or is unstable. This is a problem with the board itself, not the outlet.	The board needs repair. It can’t be fixed by yourself.
set volt xx / volt adjust	ASIC selects voltage for chips — normal	There is no need to do anything.
volt too low for chain X	This board does not have enough power to operate stably	Check the power supply. If the power supply is normal, the board is degrading, and repairs are needed.

Power Limit

What can be seen in the logs	What does it mean	What to do
power limit reached	The ASIC itself reduced the power because the PSU can’t handle it or the power supply is sagging	Check: 1) the power supply temperature; 2) the 220V network; 3) if the problem persists, change the power supply.
limited power mode	Economy mode has been activated — the hashrate will decrease	Check the power supply.

Connecting to the pool

What can be seen in the logs	What does it mean	What to do
stratum connect	ASIC is trying to connect to the pool	Normal
stratum connected	Connection to the pool successful	Everything is fine — it’s mining.
stratum authenticate success	ASIC has been authorized (Worker is correct)	Normal

Network problems (cable, internet, DNS)

What is visible	What does it mean	What to do
socket connect failed	The ASIC can’t connect to the pool. There’s no internet connection.	1. Check the cable. 2. Check the router. 3. Try a different pool.
reconnecting…	ASIC loses connection and tries to reconnect	The internet is unstable. Check the network.
DNS resolve failed	ASIC cannot find the pool domain (DNS problem)	Change DNS in the router: 8.8.8.8 / 1.1.1.1.
stratum connection interrupted	The connection was lost	Check the internet, cable, plug.
network error, retry after 10 seconds	There is internet, but it is unstable	Check ping/latency.

Problems with the pool (authorization errors or the pool itself is down)

What is visible	What does it mean	What to do
stratum authentication failed	Incorrect Worker or password (usually “x”)	Check the worker string on the pool.
pool 0 slow/down	The pool is not responding or is slow	Change pool / wait.
null work received	Pool sent an empty task	The problem is on the pool side.
pool failed: retry after …	ASIC cannot exchange data with the pool	Check network → try another pool.

Share and confirmation errors

What is visible	What does it mean	What to do
accepted share	The pool accepted the shares — everything works	Normal
rejected share	The pool deflects part of the shares	If >3% → check the Internet (delays).
stale share	Outdated shares — ASIC sent them too late	Network latency issue. Check your provider.
high stale rate	Too many outdated shares	There’s not enough internet. Change the router or cable.

Key symptoms when an ASIC doesn’t mine, but appears to be working

What is visible	What does it mean	What to do
hashrate now = 0, but fans are spinning	ASIC does not receive tasks from the pool	Check network/pool/DNS.
No accepted share in 1–2 minutes	The ASIC is connected, but does not perform any work	There is a problem with the pool or authorization.
Constant reconnecting	The internet is “floating”	Check the cable, router, change the port.
socket send error	ASIC can’t send shares to the pool	Check the network.

The most common reasons for rebooting (watchdog)

What can be seen in the logs	What does it mean	What to do
watchdog: restart miner	ASIC froze or stopped counting → watchdog was forced to restart	Look 10–30 lines above: temperature? CRC? power? network?
restart bmminer	The miner itself crashed (as a program)	This often happens due to poor power supply or chip errors. Check the power supply → check the CRC.
power lost, reboot	The power supply dropped/disappeared, the ASIC restarted	Check the socket, cable, power supply.
fatal error, rebooting	Hard hardware error	See which chain or sensor failed → usually repair.

Reboot due to temperature

What is visible	What does it mean	What to do
temp too high, reboot	ASIC overheated and turned on protection	Check ventilation, dust, room temperature.
overheat, shutdown, reboot	Chips or board exceeded the limit	Cool first, then test.
fan lost, reboot	Fan not working → security → reboot	Check fans, cables, ports.

Reboot due to power supply (PSU, 220V drop)

Log	What does it mean	What to do
power low, reboot	The power supply can’t cope, there is little voltage	Check the 220V network, remove extension cords, replace the power supply.
voltage too low, restart	Deep power supply drop	The same.
psu error, reboot	The power supply is not working properly	95% of cases → change the power supply.

Reboot due to chips, board (chain)

What is visible	What does it mean	What to do
chain X asic status abnormal, reboot	The board is frozen or the chips are not responding	View CRC, temperature, and unsatisfactory chip.
CRC error … restart	The chain is falling apart, the chips are transmitting errors	Board repair.
chain X lower hash, restart	The board has dropped in hashrate → watchdog considers this a failure	Check the board (temperature, CRC, bad chip).
fault on chain X, reboot	Hard chain error	Board for repairs.

Reboot due to network, pool

What is visible	What does it mean	What to do
stratum disconnect, reboot	ASIC loses the pool and thinks it is “dead”	Check the Internet, DNS, router.
no active pool, reboot	ASIC did not find a single working pool	Fix worker string, change pool.

PIC (microcontroller on board) errors

What can be seen in the logs	What does it mean	What to do
read pic fail	The controller does not receive data from the PIC	Board for repair. Not repairable at home.
pic init fail	PIC failed to start on startup	Board repair / PIC firmware on the stand.
pic sensor error	PIC cannot read the temperature sensor	Check the cable → if that doesn’t help, repair the board.

Temperature sensor errors

What is visible	What does it mean	What to do
temp sensor error	ASIC does not see the temperature sensor	Check the cables. If they’re connected to the board, repair.
read temp fail	Error reading the sensor	The same.
sensor connection lost	The sensor is not responding	Check the cable → repair the board.
board temp abnormal	The sensor gives incorrect readings	The board is unstable → for repair.

Controller errors (control board)

Log	What does it mean	What to do
control board lost chain	The controller does not see the board	Reconnect the cables. If that doesn’t help, repair the board or controller.
control board reboot	Controller failure	Firmware / factory reset.
control board error	The controller is unstable	Reflash. If it remains, replace the controller.
gpio init error	The controller cannot initialize the board control lines	Typical for S17/T17. Almost always a board repair.

EEPROM errors

In short: if you see the word EEPROM in the logs, you can immediately take the board in for repair.

What is visible	What does it mean	What to do
EEPROM error	EEPROM is not readable or damaged	Repairing the board or reprogramming the EEPROM on the programmer.
eeprom data invalid	The data is corrupted	The same.
eeprom not found	EEPROM not detected	The board is faulty → repair.

Antminer ASIC models with unique logs: ANTMINER S19, S19 Pro, S19j, XP

Model	Unique error	What does it mean	What to do
S19 series	start autotune	Starting frequency autotune	Normal
S19 series	start voltage tune	Setting up circuit voltages	Normal
S19 series	voltage calibration	Calibration of voltage on boards	Observe if the error does not recur.
S19/S19j	asic index abnormal	Chip order failure	Check CRC, possibly repair.
S19/S19j	hashboard mismatch	The board does not match the firmware/model	Check the firmware, compatibility, sometimes the board is not original.
S19/S19 XP	domain voltage abnormal	Poor chain nutrition	Board for repair.
S19 Pro	pic init fail	PIC does not start	Board repair.

ANTMINER S21, T21, PRO

Model	Unique error	What does it mean	What to do
S21/T21	VRM protection triggered	VRM power protection has been triggered	The board is faulty → repair.
S21/T21	overcurrent on chain	Too much current on the board	Check the power supply, most likely it needs repair.
S21/T21	domain voltage unstable	The voltage is jumping	The board is degrading → repair.
S21/T21	chip detect timeout	The chips did not initialize on time	Check the cable → repair the board.
S21/T21	critical temp: hashing stopped	The temperature has reached a critical level	Check cooling.

ANTMINER L7 (LTC/DOGE)

Model	Unique error	What does it mean	What to do
L7	L7: pll error	PLL frequency is not set	Board for repair or reduce the frequency.
L7	L7 autotune fail	Autotune couldn’t find the frequencies	Check power supply, temperature.
L7	chip temp abnormal	Problem with board temperature sensor	Check sensors → repair.
L7	fan lost	Fan loss critical for the L7	Check the fans.

ANTMINER HYDRO

Model	Unique error	What does it mean	What to do
S19 Hydro / S21 Hydro	water temp high	The water is overheated	Check the cooling circuit.
Hydro	pump speed low	The pump is running too slowly	Check the pump.
Hydro	flow sensor error	There is no water flow	Stop work → repair circuit.
Hydro	water cooling protect	Water cooling protection has been triggered	Fix the cooling problem.
Hydro	ERROR_WATER_REVERSE	Water cooling protection has been triggered	Swap the return and supply lines.