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Grandpa docs

Look up any call, event, or storage item with code examples. Runtime v472 · Block #9,197,056

Grandpa

See [`Pallet::report_equivocation`].

Index: 4 23 items

Calls 3

report_equivocation

call details

Reports GRANDPA voter equivocation (double voting) with ownership proof.

Parameters

Name	Type	Format	Description
`equivocation_proof`	`EquivocationProof`	—	equivocation_proof (EquivocationProof)
`key_owner_proof`	`Void`	—	key_owner_proof (Void)

// ----------------------------------------------------------------------
// HEADS UP: 1 arg below has a complex type with no usable default.
// Look for `undefined as any` and replace it with real value
// before running — the snippet compiles, but will fail at runtime as-is.
// ----------------------------------------------------------------------
import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Build report_equivocation call (typed, named args)
const equivocation_proof = undefined as any /* EquivocationProof — replace with real value */;

const tx = api.tx.Grandpa.report_equivocation({
  equivocation_proof,
});

report_equivocation_unsigned

call details

Reports GRANDPA equivocation without requiring a signed transaction.

Parameters

Name	Type	Format	Description
`equivocation_proof`	`EquivocationProof`	—	equivocation_proof (EquivocationProof)
`key_owner_proof`	`Void`	—	key_owner_proof (Void)

// ----------------------------------------------------------------------
// HEADS UP: 1 arg below has a complex type with no usable default.
// Look for `undefined as any` and replace it with real value
// before running — the snippet compiles, but will fail at runtime as-is.
// ----------------------------------------------------------------------
import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Build report_equivocation_unsigned call (typed, named args)
const equivocation_proof = undefined as any /* EquivocationProof — replace with real value */;

const tx = api.tx.Grandpa.report_equivocation_unsigned({
  equivocation_proof,
});

note_stalled

call details

Signals that GRANDPA finality has stalled and schedules a forced authority set change.

Parameters

Name	Type	Format	Description
`delay`	`u32`	Integer	delay: Block number
`best_finalized_block_number`	`u32`	Integer	best_finalized_block_number: Block number

Modifies: PendingChange/ Stalled/ NextForced

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Build note_stalled call (typed, named args)
const delay = 0;
const best_finalized_block_number = 0;

const tx = api.tx.Grandpa.note_stalled({
  delay,
  best_finalized_block_number,
});

Events 3

NewAuthorities

event details

Emitted when a new GRANDPA authority set becomes active.

When it fires

Session change triggered authority set rotation
New validators have been selected for GRANDPA

Fields

Name	Type	Format	Description
`authority_set`	`Vec<(Public, u64)>`	Array of (Public, u64)	New set of GRANDPA authorities (public keys with voting weights)

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Subscribe to NewAuthorities events
client.finalizedBlock$.subscribe(async (block) => {
  const events = await api.event.Grandpa.NewAuthorities.get(block.hash);
  for (const evt of events) {
    console.log("NewAuthorities:", evt.payload);
  }
});

Paused

event details

Emitted when GRANDPA finality is paused by governance.

When it fires

GRANDPA was previously live (not already paused)
Governance or root triggered the pause

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Subscribe to Paused events
client.finalizedBlock$.subscribe(async (block) => {
  const events = await api.event.Grandpa.Paused.get(block.hash);
  for (const evt of events) {
    console.log("Paused:", evt.payload);
  }
});

Resumed

event details

Emitted when GRANDPA finality resumes after being paused.

When it fires

GRANDPA was previously paused
Governance or root triggered the resume

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Subscribe to Resumed events
client.finalizedBlock$.subscribe(async (block) => {
  const events = await api.event.Grandpa.Resumed.get(block.hash);
  for (const evt of events) {
    console.log("Resumed:", evt.payload);
  }
});

Storage 7

Authorities

storage details

List of current GRANDPA authorities (public keys with voting weights).

Modifier: Default Keys: 0 Returns: WeakBoundedVec

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Query Authorities storage (no keys - plain value)
const result = await api.query.Grandpa.Authorities.getValue();
console.log("Authorities:", result);

CurrentSetId

storage details

Monotonically increasing counter for GRANDPA authority set changes.

Modifier: Default Keys: 0 Returns: u64 (Integer)

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Query CurrentSetId storage (no keys - plain value)
const result = await api.query.Grandpa.CurrentSetId.getValue();
console.log("CurrentSetId:", result);

NextForced

storage details

Next block number where a forced authority change can be signaled.

Modifier: Optional Keys: 0 Returns: u32 (Integer)

Modified by: note_stalled

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Query NextForced storage (no keys - plain value)
const result = await api.query.Grandpa.NextForced.getValue();
console.log("NextForced:", result);

PendingChange

storage details

Scheduled authority set change waiting to be applied.

Modifier: Optional Keys: 0 Returns: StoredPendingChange

Modified by: note_stalled

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Query PendingChange storage (no keys - plain value)
const result = await api.query.Grandpa.PendingChange.getValue();
console.log("PendingChange:", result);

SetIdSession

storage details

Maps GRANDPA set ID to the session index when that set was last responsible.

Modifier: Optional Keys: 1 Returns: u32 (Integer)

Keys

Name	Type	Format	Description
`key1`	`u64`	Integer	—

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Query SetIdSession storage
const key1 = 0n;

const result = await api.query.Grandpa.SetIdSession.getValue(key1);
console.log("SetIdSession:", result);

Stalled

storage details

Indicates GRANDPA has stalled with (delay, best_finalized_block).

Modifier: Optional Keys: 0 Returns: (u32, u32)

Modified by: note_stalled

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Query Stalled storage (no keys - plain value)
const result = await api.query.Grandpa.Stalled.getValue();
console.log("Stalled:", result);

State

storage details

Current state of the GRANDPA authority set (Live, Paused, or PendingPause/Resume).

Modifier: Default Keys: 0 Returns: StoredState

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Query State storage (no keys - plain value)
const result = await api.query.Grandpa.State.getValue();
console.log("State:", result);

Constants 3

MaxAuthorities

constant details

Maximum number of GRANDPA authorities allowed.

Type: u32

Value: 32

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Query MaxAuthorities constant
const value = await api.constants.Grandpa.MaxAuthorities();
console.log("MaxAuthorities:", value);

MaxNominators

constant details

Maximum nominators per validator for GRANDPA key ownership proofs.

Type: u32

Value: 20

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Query MaxNominators constant
const value = await api.constants.Grandpa.MaxNominators();
console.log("MaxNominators:", value);

MaxSetIdSessionEntries

constant details

Maximum entries kept in the SetIdSession mapping.

Type: u64

Value: "0"

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Query MaxSetIdSessionEntries constant
const value = await api.constants.Grandpa.MaxSetIdSessionEntries();
console.log("MaxSetIdSessionEntries:", value);
// Balance: divide by 10^9 for TAO
const tao = value / 1_000_000_000n;

Errors 7

PauseFailed

error details #0

Cannot pause GRANDPA because it's already paused or pending.

Common Causes

Already paused
PendingPause scheduled

How to Fix

Check Grandpa.State,Wait for pending change

ResumeFailed

error details #1

Cannot resume GRANDPA because it's not paused.

Common Causes

Already Live
PendingResume scheduled

How to Fix

Check Grandpa.State,Wait for pending change

ChangePending

error details #2

An authority set change is already pending.

Common Causes

Session change scheduled
Previous forced change pending

How to Fix

Check Grandpa.PendingChange,Wait for current change

TooSoon

error details #3

Cannot signal forced change; minimum delay not met.

Common Causes

Recent forced change
NextForced not reached

How to Fix

Check Grandpa.NextForced,Wait for delay

InvalidKeyOwnershipProof

error details #4

Key ownership proof in equivocation report is invalid.

Common Causes

Wrong session
Proof corrupted
Session data pruned

How to Fix

Verify session matches,Check SetIdSession,Report promptly

InvalidEquivocationProof

error details #5

Equivocation proof doesn't demonstrate double voting.

Common Causes

Bad signatures
Same block
Wrong round

How to Fix

Verify signatures,Ensure different blocks,Check round

DuplicateOffenceReport

error details #6

This equivocation was already reported.

Common Causes

Another reporter was faster
Resubmitting

How to Fix

No action needed - offender will be slashed