# weights_version (/docs/hyperparameters/weights-version)

`weights_version` (on chain: `WeightsVersionKey`) is a version gate on weight
submissions. Subnet owners raise it when they ship a breaking change to their
validator code: any validator still running the old software — and therefore
sending an old version key — has its weights rejected until it upgrades.

## How it works [#how-it-works]

Every `set_weights` call carries a `version_key` argument. The chain compares
it in `check_version_key` (`pallets/subtensor/src/subnets/weights.rs`): the
submission passes when the subnet's `WeightsVersionKey` is 0 (the gate is
disabled) or when the submitted key is greater than or equal to it. Otherwise
the call fails with `IncorrectWeightVersionKey`. The value itself is opaque to
the chain — it is a plain u64 counter whose meaning is a convention between
the owner and their validator codebase.

The key is checked at reveal time too: revealed commit-reveal weights pass
through the same `set_weights` validation, so a version bump between commit
and reveal invalidates in-flight commits.

The SDK does not preflight this check — `btcli tx set-weights` (the
`set_weights` intent) sends `version_key` 0 unless told otherwise, which only
passes on subnets that leave the gate disabled. Validator code on gated
subnets must pass the current key explicitly.

Changing it has a dedicated rate limit: the owner may update it at most once
per `WeightsVersionKeyRateLimit` tempos (currently 5).

Raise the required key to watch validators on old software fall off:

<HyperparamWeightsVersionGate />

## Reading and setting [#reading-and-setting]

```bash
btcli sudo get --netuid N --name weights_version
```

Owner-settable; the value is a plain integer:

```bash
btcli sudo set --netuid N --name weights_version --value 1020
```

## Related [#related]

* [`min_allowed_weights`](/docs/hyperparameters/min-allowed-weights) — the floor on submission size
* [`max_weights_limit`](/docs/hyperparameters/max-weights-limit) — cap on any single weight
* [`weights_rate_limit`](/docs/hyperparameters/weights-rate-limit) — how often submissions are accepted
* [`commit_reveal_period`](/docs/hyperparameters/commit-reveal-period) — the commit-to-reveal delay the key must survive