Slashing, penalties and downtime: what can go wrong when you run a validator
By AVADO team · Published
Going offline is cheap for an Ethereum validator: you lose roughly what it would have earned in that time, and nothing more. Your stake isn’t at risk. Slashing is different: it only happens when a validator signs conflicting messages, almost always because the same validator keys are running on two machines at once. Since the Pectra upgrade in May 2025, the initial slashing penalty is 1/4,096 of the validator’s balance (Electra specification), about 0.008 ETH for a 32 ETH validator, but a slashed validator is also forced to exit.
What happens when my validator goes offline?
Downtime means missed attestations: the votes a validator casts on the chain every few minutes. While offline, your validator doesn’t earn the rewards for them, and it pays a small penalty of about the same size. So if you are offline for a day, you lose about a day’s rewards. When you come back online, you start earning again.
| Situation | What you lose | Is your stake at risk? |
|---|---|---|
| Offline for a few hours or days | About what you would have earned in that time | No |
| Offline while the whole network can’t finalise (rare) | Penalties grow the longer this lasts (the “inactivity leak”) | Only in a long network-wide failure |
| Slashed | An initial penalty, a possible correlation penalty, penalties until you exit, and a forced exit | Partly |
A power cut, an internet outage or a reboot for updates is not a slashing offence.
What is slashing?
Slashing is how Ethereum punishes a validator for provably breaking the rules. There are three ways to get slashed:
- Proposing two different blocks for the same slot.
- Attesting to two different blocks for the same target (a double vote).
- Making an attestation that surrounds another one (a surround vote).
Honest validators running on one machine don’t do any of these. In practice, home stakers get slashed when the same keys run in two places, for example after moving to new hardware without stopping the old machine, or after importing keys into a second client “just in case”.
How much does slashing cost?
The cost of slashing is made up of three parts:
- An initial penalty of 1/4,096 of its effective balance. Before Pectra this was 1/32. For a 32 ETH validator it is now about 0.008 ETH; for a validator with 2,048 ETH it is 0.5 ETH. (Chorus One explains the change.)
- A correlation penalty about halfway through the exit period. It depends on how many other validators were slashed around the same time. If you are the only one, it is close to zero. If many validators are slashed together, for example after a big operator’s mistake, it can be much larger.
- Missed rewards and small penalties until the validator can withdraw, which takes about 36 days, according to ethereum.org.
The validator is then removed from the validator set and can’t be used again. Your remaining ETH goes to your withdrawal address.
How do I avoid getting slashed?
Avoiding slashing is mostly about never running the same keys in two places.
- Never run the same validator keys on two machines, not even for a minute.
- Moving to new hardware: stop the validator on the old machine and make sure it can’t start again, for example by removing the keys or wiping the disk. Wait at least two epochs (about 13 minutes) before starting the validator on the new machine.
- Keep the slashing protection database. Your validator client records what it has signed. When you move keys, export the slashing protection data (the EIP-3076 interchange format) from the old client and import it with the keys.
- Don’t use a “backup” validator. Being offline for a while costs little. Running a second copy costs far more.
- Keep an offline backup of your mnemonic. It lets you regenerate your keys and your withdrawal credentials if the hardware fails.
How does AVADO help?
Your validator keys stay on your AVADO, and the client packages include slashing protection. The AVADO documentation has guides for importing keys, setting your withdrawal address and exiting a validator. Priority Care includes a guided move to new hardware once a year, so someone from the team goes through the migration with you, and email alerts when your box goes offline, so short outages don’t turn into long ones.