How to fix rejected shares in mining?

"Rejected shares in crypto mining occur when submitted work is invalid or delayed, often due to latency, high difficulty, or unstable hardware, reducing profitability."

Jul 18, 2025 at 12:15 am

Understanding What Rejected Shares Mean in Mining

In the world of cryptocurrency mining, rejected shares refer to the mining work submitted by a miner that is not accepted by the mining pool. These shares typically occur when the solution provided by the miner arrives too late or does not meet the required difficulty threshold set by the pool. The most common reason for rejection is network latency, which causes the share to arrive after the block has already been solved. A high rejection rate can significantly reduce mining profitability, so it's crucial to understand how to mitigate this issue.

Common Causes of Rejected Shares

Several factors contribute to rejected shares during mining operations:

• Network Latency: If your connection to the mining pool server is slow or unstable, your shares may be submitted too late.
• High Pool Difficulty: Some pools offer adjustable difficulty settings. If your hardware isn't powerful enough to solve shares within the given time, they get rejected.
• Outdated Mining Software: Older versions of mining software might not communicate efficiently with the pool.
• Hardware Instability: Overclocked or unstable GPUs/ASICs can produce invalid results or delay submissions.
• Firewall or Antivirus Interference: Sometimes, security software blocks or delays communication between the miner and the pool.

Identifying the root cause is essential before applying any fixes.

Optimizing Network Settings to Reduce Rejection

To minimize network-related issues, consider the following steps:

• Choose a Nearby Mining Pool Server: Most pools provide multiple regional servers. Connecting to one geographically closer reduces ping times.
• Use a Wired Ethernet Connection: Wireless connections are more prone to interference and instability compared to wired setups.
• Improve Internet Bandwidth: Ensure your upload speed is sufficient for mining traffic. A minimum of 1 Mbps upload speed per GPU is recommended.
• Monitor Ping Times: Use tools like ping or tracert to monitor latency to the mining pool. Anything above 100ms could increase rejection rates.

These adjustments help ensure timely submission of valid shares.

Adjusting Mining Difficulty and Stratum Settings

Mining pools allow miners to adjust the difficulty level of the shares they receive. Here’s how you can optimize this setting:

• Lower the Difficulty: This allows your hardware to submit shares faster, reducing the chance of timeout.
• Enable Custom Difficulty: In mining software like Claymore or NiceHash, check if custom difficulty settings are available and tweak them based on your hashrate.
• Switch to a Different Stratum Protocol: Some pools support different stratum protocols (like stratum+tcp:// or stratum+ssl://). SSL connections can sometimes introduce latency; try switching to non-SSL if possible.

You should experiment with these options while monitoring your rejection rate in real-time through the mining dashboard.

Updating and Configuring Mining Software Properly

Using outdated or improperly configured mining software can lead to communication errors with the pool. Follow these steps:

• Update Your Miner: Whether you're using CGMiner, BFGMiner, PhoenixMiner, or lolMiner, always use the latest stable version.
• Check Configuration Files: Review your .bat or .conf files for typos in the pool address, port, wallet address, or worker name.
• Use Reliable Mining Tools: Stick to well-known and actively maintained mining clients to avoid compatibility issues.
• Disable Unnecessary Features: Features like API monitoring or remote management can sometimes interfere with normal mining operations.

Correct configuration ensures smooth communication between your hardware and the mining pool.

Ensuring Hardware Stability and Performance

Unstable or overheating hardware can result in rejected or stale shares. To prevent this:

• Monitor Temperatures: Use tools like MSI Afterburner or HWInfo to track GPU temperatures. Excessive heat can cause throttling or crashes.
• Stress Test Your Hardware: Run stress tests using mining benchmarks or synthetic workloads to identify instability.
• Avoid Aggressive Overclocking: While overclocking boosts performance, it may compromise stability. Find a balance between speed and reliability.
• Ensure Sufficient Power Supply: An underpowered PSU can lead to inconsistent hash rates and rejected shares.

Regular maintenance and optimization of your mining rig play a vital role in minimizing rejections.

Frequently Asked Questions

What is the difference between rejected shares and stale shares?

Rejected shares are those that fail validation due to incorrect solutions or timeouts. Stale shares, on the other hand, are valid but submitted after the block has already been found by another miner.

Can firewall settings really affect my mining performance?

Yes, firewalls or antivirus programs can block or delay outbound connections from your mining software, leading to increased rejected shares. Whitelisting your miner in firewall settings often resolves this issue.

Is there a way to see rejected shares in real-time?

Most modern mining software displays rejected shares directly in the console output or via an API interface. Additionally, mining pool dashboards usually show detailed statistics including rejection rates.

Should I switch mining pools if I have consistent rejected shares?

Before switching pools, ensure all local configurations are optimized. However, if the problem persists and other users on the same pool do not face similar issues, changing to a more stable or regionally closer pool may help.