What is a stale or rejected share?
A stale share is mining work that reaches your mining pool too late to count as current work. A rejected share is work the pool does not accept, whether because it is stale or for another reason. A few can happen during normal mining, but a steady stream is worth checking because that work may not earn you anything.
What a share actually proves
When you mine Monero through a mining pool, you join other miners and share rewards under the pool’s payment rules. A share is a small proof that your device has been doing the calculations the pool asked for.
Most shares do not find a Monero block. Instead, they help the pool measure your contribution.
Think of a share as a work receipt:
- Accepted: The pool checked your receipt and counted it.
- Stale: Your receipt arrived after the relevant work had changed.
- Rejected: The pool did not count your receipt, for a stated reason.
These labels can overlap. One pool might list stale shares separately, while another includes them in its rejected total.
Why a share becomes stale
Your miner works on a job, which is a set of instructions for trying to find the next block. When the network finds a new block, the pool sends updated instructions.
If your device is still working on the old job, or its result is delayed on the way back, a share can arrive too late.
Common causes include:
- A slow or unstable internet connection.
- A pool server far from you.
- Brief connection drops or slow updates from the pool.
- Your device sleeping or pausing the mining software.
Monero finds a block about every two minutes on average, not on a fixed schedule. There will sometimes be a small window where your miner and the pool are switching jobs. That makes occasional stale shares unsurprising.
A stale share does not necessarily mean your device calculated anything incorrectly. Often, the timing was simply unlucky.
Why other shares get rejected
Not every rejected share is stale. The pool’s error message is your best clue.
You might see reasons such as:
- Low difficulty: The result did not meet the pool’s required level of work.
- Duplicate share: The same result was submitted more than once.
- Invalid result: The calculation did not pass the pool’s checks.
- Unknown job: The submission referred to a job the pool no longer recognized.
Possible causes include outdated mining software, incorrect settings, or unstable hardware. Overclocking, which means running hardware faster than its standard settings, can cause calculation errors if it makes your device unstable.
What you should check
Start with the pool’s dashboard and your miner’s messages. Look at the rejection reason and the percentage over a meaningful period—not just one rejected share shortly after startup.
If you mine in a browser, check whether switching tabs, putting the device to sleep, or your browser’s power-saving features interrupts mining.
Then try these steps:
- Use a stable connection and a nearby supported pool server.
- Update your mining software.
- Return any hardware speed tweaks to standard settings.
- Check the pool’s instructions and how it handles stale shares.
Payment policies differ. Some pools give certain stale shares partial credit; others give none. Rejections reduce your credited work, not coins already held in your wallet.
The bottom line
A stale share is usually a timing problem. Other rejected shares may point to settings, software, or hardware trouble. Check the reason before changing anything, and focus on persistent patterns rather than an occasional missed share.
