Skip to main content

Other Runtime Changes Changelog - v7.4 to v8.0

This page covers v8 changes not significant enough for their own page, but still worth knowing about. It is part of the v7.4 → v8.0 changelog.

Audience: anyone doing a thorough audit of chain-level changes; most integrators can skip this page unless a specific item below is relevant to them.

Transaction fees split into two pallets​

Polymesh's custom transaction-payment pallet (pallets/transaction-payment, crate pallet-transaction-payment at v7.4) is renamed to crate polymesh-transaction-payment and slimmed down. Chain v8 mounts it alongside the standard upstream pallet_transaction_payment:

  • TransactionPayment (runtime index 6) — the standard upstream pallet: weight-to-fee conversion, the next-fee-multiplier adjustment, and the RPC fee-query helpers (query_info, query_fee_details, compute_fee, etc.) that used to live in Polymesh's own pallet.
  • PolymeshTransactionPayment (runtime index 51) — what's left of the Polymesh-specific pallet: current_payer/set_current_payer (tracks who is paying for the current extrinsic, used by the subsidy system) and the set_disable_fees call.

If you called the RPC-style fee-query helpers directly against the old TransactionPayment pallet, they now live on the standard upstream pallet at the same pallet name but different index; set_disable_fees and payer-tracking move to PolymeshTransactionPayment.

The upstream TransactionPayment pallet also brings its own constant and storage: new constant OperationalFeeMultiplier (multiplies the priority "virtual tip" for Operational-class extrinsics), and new transient storage TxPaymentCredit (cleared every block; not user-facing state). Polymesh's old fee-curve constants TransactionByteFee and WeightToFeeConst are removed — fee-per-byte and the weight-to-fee curve are now configured through the upstream pallet's own WeightToFee/LengthToFee mechanism instead.

Sudo moved to the upstream standard; gains remove_key​

Same pattern as Balances/Staking: the local pallets/sudo crate is deleted, and Sudo is now the standard upstream pallet-sudo. sudo, sudo_unchecked_weight, set_key, and sudo_as are unchanged. New: remove_key(), which permanently and irreversibly clears the sudo key, and a corresponding KeyRemoved event.

System: authorized runtime upgrades, and ExtrinsicSuccess/ExtrinsicFailed retyped​

frame_system gains a two-step upgrade path: authorize_upgrade(code_hash) (or authorize_upgrade_without_checks) pre-authorizes a specific code hash, and anyone can subsequently call apply_authorized_upgrade(code) with the matching Wasm blob to perform the upgrade. New events UpgradeAuthorized and RejectedInvalidAuthorizedUpgrade; new errors MultiBlockMigrationsOngoing, NothingAuthorized, Unauthorized; new storage AuthorizedUpgrade (holds the pending authorization), BlockSize, BlocksTillUpgrade, InherentsApplied, and ExtrinsicWeightReclaimed; removed storage AllExtrinsicsLen. This is primarily relevant to governance/infrastructure tooling that performs runtime upgrades, not typical integrations.

More broadly relevant: ExtrinsicSuccess { dispatch_info } and ExtrinsicFailed { dispatch_error, dispatch_info } — emitted once per extrinsic in every block — change dispatch_info's type from DispatchInfo to DispatchEventInfo. The fields (weight, class, pays_fee) are the same; the type name itself changes, which matters for typed decoders generated from chain metadata even though the underlying encoding is unaffected.

Transaction extension: CheckMetadataHash (Merkleized metadata)​

Chain v8 adds the CheckMetadataHash transaction extension (frame_metadata_hash_extension::CheckMetadataHash) to the runtime's signed-extension tuple. This implements the "Merkleized metadata" scheme (RFC-0078): the production runtime is built with a hash of its own metadata baked in, and a signer can opt to include that metadata hash in the signed payload.

This is the chain-level change that makes generic offline signers and hardware wallets able to decode and display full, human-readable Polymesh transaction details without a Polymesh-specific application — the device verifies the metadata it uses to render the transaction against the hash committed in what it signs. In practice this is what enables the generic Polkadot Ledger app (and similar tooling) to sign Polymesh transactions safely; see the Ledger Hardware Wallet guide for the wallet-side view.

Because compatible signers decode against the runtime's own metadata rather than a fixed, hardcoded set of transaction formats, future runtime upgrades that add or change transaction types are typically understood and displayed correctly without requiring an app update — the metadata hash simply changes to match the new runtime.

Impact on transaction construction:

  • The signed-extension list gained one entry, CheckMetadataHash, which contributes one byte (its mode: enabled/disabled) to the extra/additional-signed data. Anything that builds and signs extrinsics by manually assembling the signed extensions must account for it, in the correct position within the tuple, or signatures will be rejected.
  • The extension supports two modes. With the mode disabled, only the mode byte is added and no metadata hash is required — existing signing flows continue to work with just the extra byte accounted for. With the mode enabled, the metadata hash is included, which is what unlocks the human-readable display on compatible signers.
  • Up-to-date client libraries handle this automatically using the chain's current metadata (which carries the information needed to compute the hash); the Polymesh SDK and current Polkadot-JS tooling already account for it.

Scheduler: retry management​

New calls set_retry, set_retry_named, cancel_retry, cancel_retry_named let a scheduled task be configured to automatically retry (with a configurable period and retry count) if it fails. New events RetrySet, RetryCancelled, RetryFailed, AgendaIncomplete, backed by new Retries storage.

Preimage: ensure_updated​

New call ensure_updated(hashes) re-checks and updates the status of the given preimage hashes; the caller pays no fee if at least 90% are successfully updated. New storage RequestStatusFor; new errors TooMany, TooFew.

Indices: poke_deposit​

New call poke_deposit(index) re-syncs the deposit held for a short/vanity account index after a deposit-price change, refunding or charging the difference. New event DepositPoked. Low relevance unless you use short indices.

New light-client pallets: Beefy, Mmr, MmrLeaf​

Three new pallets support BEEFY (a secondary finality gadget for efficient light-client / bridge proofs) and its Merkle Mountain Range leaf data. This is what requires the new BEEFY session key covered in Staking & Validators. Also new: MultiBlockMigrations, infrastructure for running storage migrations across multiple blocks rather than one.

MultiSig: one error removed​

ChangeNotAllowed is removed, with no replacement. No calls, events, or storage on MultiSig changed — this is the only difference.

Removed: Bridge pallet (dead code)​

The local pallets/bridge crate is deleted. It was already commented out of construct_runtime! at v7.4.0 (//Bridge = 16,) — it was source code that was never compiled into any runtime, so this has no practical impact.

Migration checklist​

  1. If you query transaction fees via RPC-style calls, note they now resolve against the standard TransactionPayment pallet rather than Polymesh's custom one; current_payer and set_disable_fees move to PolymeshTransactionPayment. Drop any reliance on TransactionByteFee/WeightToFeeConst.
  2. If your tooling calls Sudo calls by pallet name/index, re-check — the pallet moved to the upstream standard.
  3. If you build or apply runtime upgrades programmatically, consider the new authorize_upgrade/apply_authorized_upgrade two-step path for large runtimes.
  4. If you decode ExtrinsicSuccess/ExtrinsicFailed with generated types, regenerate them for the DispatchInfo → DispatchEventInfo rename.
  5. If you construct and sign extrinsics by manually assembling signed extensions (rather than via the SDK or up-to-date Polkadot-JS), add the new CheckMetadataHash extension in the correct tuple position, or signatures will be rejected. Regenerating against the chain's current metadata handles this for you.
  6. No action needed for Bridge — it was already inert.

For the complete literal list of every added/removed/modified call, event, error, storage item, and constant across every pallet, including the smaller ones not otherwise covered by this changelog series (Babe, Grandpa, Historical, Offences, Permissions, Pips, ElectionProviderMultiPhase, AuthorityDiscovery, ImOnline, committee-membership pallets, and Base), see the Full Pallet API Reference.