If you are asking “why are my mining shares rejected,” the short answer is that your miner submitted work the mining pool could not accept. This can happen because the share arrived too late, was calculated incorrectly, was submitted twice, or was sent with the wrong mining configuration. A few rejected shares can happen in normal mining, but a rising rejection rate can reduce your effective hashrate and may lower your actual mining rewards.

For miners, rejected shares are not just a dashboard detail. They show the difference between hashrate your machine appears to produce and hashrate the pool can actually use. This FAQ explains the main causes, what to check first, and how to reduce rejected shares in a practical way.

What does it mean when mining shares are rejected?

A mining share is proof that your miner is doing work for a mining pool. The share does not have to find a full block. It only needs to meet the pool’s assigned difficulty target, so the pool can measure your contributed hashrate and calculate rewards under its payout rules.

A rejected share is a submitted share that the pool does not count as valid work. The miner may still have spent electricity and time producing it, but the pool cannot credit it as accepted work.

In simple terms:

• Accepted share: The pool received useful work from your miner.
• Rejected share: The pool received work it could not accept.
• Stale share: The share was valid for an old job but arrived after the pool had moved to a new job.
• Invalid share: The share failed validation, often because of hardware instability, overclocking, firmware issues, or incorrect settings.
• Duplicate share: The same share was submitted more than once, often because of software, proxy, or connection problems.

The exact labels may vary by miner software and mining pool interface, but the troubleshooting logic is similar: identify the rejection type first, then check the most likely cause.

Do rejected shares reduce mining revenue?

Rejected shares can reduce mining revenue because they lower your effective accepted hashrate. Your miner might show a high local hashrate, but the pool pays based on work it accepts under the pool’s reward system. If too many shares are rejected, less of your machine’s work is counted.

The impact depends on the rejection rate and the type of rejected share. A short spike during a network change, miner restart, or pool reconnection may not matter much. A steady rejection rate over many hours is more serious because it means wasted work is happening continuously.

Miners should look at accepted hashrate, rejected share percentage, and earnings together. A miner that looks powerful locally but has poor pool-side acceptance may be underperforming in real payout terms.

Why are my mining shares rejected most often?

The most common reasons mining shares are rejected are stale submissions, unstable hardware, network latency, duplicate submissions, and incorrect pool or miner settings.

For stale shares, the likely cause is a delay between the miner and the pool. First check latency, server region, and network stability.

For invalid shares, the likely cause is unstable mining or hardware errors. First reduce overclocking and check temperature, power, and logs.

For duplicate shares, the likely cause is repeated submission from software or connection retries. First check miner logs, proxy settings, and worker configuration.

For authorization or configuration errors, the likely cause is the wrong pool, coin, worker, port, or settings. First recheck the pool setup details and miner configuration.

1. Stale shares caused by delay

A stale share happens when your miner submits work for a mining job that is no longer current. Mining pools send new jobs when the network changes or when a new block is found. If your miner receives the update late or sends the result too slowly, the share may arrive after the pool has moved on.

Common causes include:

• High network latency between the miner and pool server.
• Unstable internet connection.
• Wi-Fi packet loss.
• Using a mining server region that is too far away.
• Router, firewall, or ISP instability.

For miners, stale shares are often a network and routing issue rather than a raw hashrate issue.

2. Invalid shares caused by unstable mining

Invalid shares usually mean the work result does not pass validation. This can happen when a miner is producing errors internally.

Common causes include:

• Overclocking too aggressively.
• Voltage settings that are too low or unstable.
• High chip temperature.
• Faulty hashboards, GPUs, risers, memory, or power supply units.
• Firmware bugs or incompatible mining software.

If invalid shares rise after changing frequency, voltage, firmware, or cooling, the change is a likely suspect. A stable miner with slightly lower hashrate may earn more than an unstable miner that reports higher local speed but produces rejected work.

3. Duplicate shares from software or connection issues

A duplicate share means the same share was submitted more than once. This can happen after connection retries, mining software bugs, proxy misconfiguration, or unstable network sessions.

Duplicate shares are usually not solved by increasing hashrate. Check miner logs, proxy settings, and whether multiple workers are accidentally using the same worker name or connection details.

4. Wrong pool, coin, worker, or difficulty settings

Rejected shares can also come from basic configuration mistakes. Examples include:

• Mining the wrong coin algorithm.
• Entering the wrong pool address or port.
• Using a worker name format the pool does not recognize.
• Using unsupported firmware or miner software settings.
• Setting difficulty in a way that does not match the pool’s requirements.

For ViaBTC users, the safest approach is to follow the current setup guide for the specific coin and miner type, then compare the miner configuration with the pool account details.

How can I troubleshoot rejected shares step by step?

Start with the simplest checks before changing hardware settings. Rejected shares can have several causes, and changing too many variables at once makes the real cause harder to find.

1. Check the pool connection

Confirm that the pool URL, port, coin, and worker name are correct. If the pool provides regional servers, choose the region with the lowest stable latency. Avoid assuming that the geographically closest server is always the best; test actual connection quality.

2. Check your internet stability

Look for packet loss, router restarts, weak Wi-Fi, ISP interruptions, or overloaded local networks. Mining equipment should use a stable wired connection whenever possible.

3. Compare miner-side and pool-side hashrate

Miner software may show local hashrate, while the pool shows accepted effective hashrate. A large gap can point to rejected shares, unstable connection, or configuration problems.

4. Read miner logs

Logs often show whether rejections are stale, invalid, duplicate, authorization-related, or connection-related. This is more useful than looking only at the final rejection percentage.

5. Return overclocked miners to stable settings

If rejected shares increased after tuning frequency, voltage, or fan settings, revert to a known stable profile. Then adjust slowly and watch accepted hashrate, temperature, and rejection rate over time.

6. Check cooling and power

High temperatures and unstable power can cause calculation errors. Inspect airflow, dust buildup, power supply capacity, cables, and ambient room temperature.

7. Test one change at a time

Change the pool server, network cable, firmware, or tuning profile separately. Wait long enough to see whether the rejection pattern improves.

ViaBTC miners can also use account and hashrate monitoring features to compare pool-side performance with local miner readings.

What rejection rate should miners watch?

There is no single universal rejection rate that applies to every coin, miner model, network condition, and pool setup. A small number of rejected shares may appear during normal operation. The warning sign is a repeated pattern: rejected shares stay elevated, increase after a configuration change, or appear together with falling accepted hashrate.

Watch these signals together:

• Rejected share percentage over several hours.
• Accepted hashrate compared with local hashrate.
• Miner temperature and hardware error logs.
• Network latency and disconnect frequency.
• Whether the issue affects one worker or all workers.

If only one machine has high rejected shares, the issue is likely local to that miner. If many workers show the same problem at the same time, check the network, router, or pool connection path.

When should I contact pool support?

Contact mining pool support when the rejection rate remains high after you have checked configuration, network stability, miner logs, temperature, and tuning settings. Support teams can usually help faster if you provide clear technical details.

Prepare the following before asking for help:

• Coin and mining algorithm.
• Miner model and firmware version.
• Pool server URL and port used.
• Worker name or account identifier.
• Screenshots of rejected share data.
• Miner logs showing rejection messages.
• Time period when the issue started.
• Any recent changes to firmware, network, or tuning.

This information helps separate pool connection issues from local hardware, network, or configuration problems.

Bottom line

Mining shares are usually rejected because the pool receives work that is late, invalid, duplicated, or incorrectly configured. The best fix depends on the share type. For stale shares, check network quality and pool server selection. For invalid shares, check overclocking, cooling, power, firmware, and hardware stability. For duplicate or authorization errors, check software and worker configuration.

A miner’s goal is not just to show the highest local hashrate. The goal is to produce stable accepted shares that the pool can count. Monitoring rejected shares, accepted hashrate, and miner logs together gives a much clearer picture of real mining performance.