changelog.md

title	IC interface spec changelog
description	Version history and changes to the IC Interface Specification
sidebar	label order Changelog 6

Changelog {#changelog}

0.67.0 (2026-08-17) {$0_67_0}

• The management canister method canister_info can now also be invoked via non-replicated (query) calls by external users and from composite query methods (it remains callable by canisters via inter-canister calls and remains rejected for ingress messages). Retrieving canister information is not subject to any access control, so any principal, including the anonymous one, can call it.

0.66.0 (2026-08-17) {$0_66_0}

• Two new paths in the certified state tree, /canister/<canister_id>/canister_creation_timestamp (the time at which the canister was created) and /canister/<canister_id>/last_install_timestamp (the time at which the canister's code was most recently deployed or a snapshot was loaded onto it), both expressed in nanoseconds since 1970-01-01. Both can be requested via read_state if <canister_id> matches the effective canister id of the request.
• Composite query methods and their callbacks can call the management canister query methods canister_status, canister_metrics, fetch_canister_logs, and list_canisters. Such a call is always executed against the state of the subnet hosting the calling canister and it is subject to the same access control as the corresponding query call submitted by a user, with the calling canister as the caller. Calls to all other management canister methods are rejected.

0.65.0 (2026-08-03) {$0_65_0}

• New canister setting status_visibility controlling who can read a canister's status via the canister_status endpoint: controllers (default) restricts access to the canister's controllers, public allows anyone, and allowed_viewers grants access to a list of up to 10 principals in addition to the controllers. The canister itself and subnet admins can always read the status.

0.64.0 (2026-07-06) {$0_64_0}

• New optional permissions field in request delegations restricting the kinds of requests the delegation applies for: the value "queries" restricts the delegation to query calls and read_state requests, so update calls carrying such a delegation in their chain of delegations are not accepted; the value "all" permits all kinds of requests, same as omitting the field. Requests of any kind carrying a delegation with any other value of the permissions field are not accepted.
• wasm_memory_threshold in canister settings is now bounded by 2⁴⁸, analogously to wasm_memory_limit.
• New canister setting minimum_incoming_canister_call_cycles: if set, inter-canister calls from a different canister that attach fewer cycles than this threshold are rejected with CANISTER_ERROR and all attached cycles are refunded. Ingress messages and self-calls are not affected.

0.63.0 (2026-06-29) {$0_63_0}

• Support for the HTTP method PATCH in canister http_request in non-replicated mode.

0.62.0 (2025-05-26) {$0_62_0}

• Inter-canister response callback messages might still be executed after the condition for canister_on_low_wasm_memory is triggered and before the function canister_on_low_wasm_memory is executed.
• Allow EdDSA on curve Ed25519 as a third WebAuthn signature scheme (alongside ECDSA P-256 and RSA PKCS#1v1.5).

0.61.0 (2025-05-18) {$0_61_0}

• New management canister endpoint canister_metrics.

0.60.0 (2025-05-04) {$0_60_0}

• Canister signatures from canisters on subnets of type cloud_engine are not valid.
• New HTTP endpoints for update calls (to create a canister by subnet admins) and query calls (to list all canisters on a subnet by subnet admins) whose URL contains the (effective) subnet ID on which the canister is created or whose canisters should be enumerated.

0.59.0 (2025-04-27) {$0_59_0}

• Update and query calls by users authenticated via canister signatures can carry auxiliary information signed by a canister signature issued by the same canister. That information is passed via a new sender_info field of the user HTTP request and available to the callee via new system API ic0.msg_caller_info_data_size, ic0.msg_caller_info_data_copy, ic0.msg_caller_info_signer_size, and ic0.msg_caller_info_signer_copy.
• Added query call for subnet admins to list all canisters on a subnet.

0.58.0 (2025-04-01) {$0_58_0}

• Added subnet admins who can start, stop, uninstall, delete a canister and request its status.

0.57.0 (2025-03-30) {$0_57_0}

• Added canister snapshot visibility settings.

0.56.0 (2025-03-16) {$0_56_0}

• Support for the HTTP methods PUT and DELETE in canister http_request in non-replicated mode.
• Added subnet type to the certified state tree at the path /subnet/<subnet_id>/type.

0.55.0 (2025-01-26) {$0_55_0}

• Support for canister renaming (required for canister ID migration from one subnet to another subnet).

0.54.0 (2025-12-15) {$0_54_0}

• The management canister's endpoint take_canister_snapshot can uninstall code atomically after taking canister snapshot.
• The canister system API ic0.msg_reject_code is available in cleanup callbacks.

0.53.0 (2025-11-24) {$0_53_0}

• New execution context TQ for canister http transform functions to specify that no IC certificate is available in such executions.

0.52.0 (2025-11-17) {$0_52_0}

• Canister memory allocation does not limit canister memory usage.

0.51.0 (2025-10-20) {$0_51_0}

• Management canister endpoint canister_status can be invoked as a query call.

0.50.0 (2025-10-13) {$0_50_0}

• Allow loading a canister snapshot onto a different canister on the same subnet.
• New management canister API providing canister metadata (contained in canister WASM custom sections).
• New HTTP handler endpoints to support canister migration (by providing sharded routing table in certificates): /api/v4/canister/<effective_canister_id>/call, /api/v3/canister/<effective_canister_id>/read_state, /api/v3/subnet/<effective_subnet_id>/read_state, and /api/v3/canister/<effective_canister_id>/query.
• The following existing HTTP handler endpoints are marked as deprecated: /api/v3/canister/<effective_canister_id>/call, /api/v2/canister/<effective_canister_id>/read_state, /api/v2/subnet/<effective_subnet_id>/read_state, and /api/v2/canister/<effective_canister_id>/query.
• Paths with prefix /subnet/<subnet_id>/canister_ranges (legacy routing table) can only be requested via the deprecated endpoints or if <subnet_id> is the root subnet.
• Paths with prefix /canister_ranges/<subnet_id> (sharded routing table) can only be requested via /api/v{2,3}/subnet/.../read_state, i.e., not via /api/v{2,3}/canister/.../read_state.
• All paths with prefix /canister_ranges/<subnet_id> must refer to the same subnet ID <subnet_id>.

0.49.0 (2025-10-06) {$0_49_0}

• Added support for non-replicated canister HTTP outcalls.

0.48.0 (2025-09-29) {$0_48_0}

• Added support for canister environment variables in canister settings and new System API for accessing environment variables (ic0.env_var_count, ic0.env_var_name_size, ic0.env_var_name_copy, and ic0.env_var_value_size).

0.47.0 (2025-09-22) {$0_47_0}

• Management canister API for downloading and uploading canister snapshots.

0.46.0 (2025-08-25) {$0_46_0}

• The management canister method canister_status returns two new fields: version indicating the canister version, and ready_for_migration indicating whether a canister's queues are empty and its streams flushed. The value only makes sense when the canister status is stopped.
• Canister history provides the source of a snapshot in the entry for loading the snapshot.

0.45.0 (2025-08-18) {$0_45_0}

• Canister ranges of every subnet are now available at a dedicated prefix /canister_ranges in the state tree, facilitating fragmentation due to canister migration.

0.44.0 (2025-08-11) {$0_44_0}

• The management canister method subnet_info returns a new field registry_version providing the registry version of the corresponding subnet.

0.43.0 (2025-07-17) {$0_43_0}

• VetKD API is considered stable.

0.42.0 (2025-06-06) {#0_42_0}

• New system API ic0.root_key_{size, copy} for fetching the public key of the IC root key.

0.41.0 (2025-06-02) {#0_41_0}

• Management canister API for threshold key derivation (vetKD).

0.40.0 (2025-05-30) {#0_40_0}

• Non-ASCII characters are allowed in the URL of canister http outcalls.
• The transformed response size of canister http outcalls must not exceeded max_response_bytes (if provided).

0.39.0 (2025-05-07) {#0_39_0}

• Threshold Schnorr API, composite query methods, and canister logs management canister API are considered stable.

0.38.0 (2025-04-18) {#0_38_0}

• Reverted a lower bound of one week on the canister's freezing threshold.

0.37.0 (2025-04-11) {#0_37_0}

• Introduced a lower bound of one week on the canister's freezing threshold.

0.36.0 (2025-03-31) {#0_36_0}

• Bounded-wait calls.

0.35.0 (2025-03-20) {#0_35_0}

• New system API ic0.canister_liquid_cycle_balance128 returning the current amount of cycles that is available for spending in calls and execution.
• A canister can have multiple snapshots.

0.34.0 (2025-03-07) {#0_34_0}

• New canister method canister_on_low_wasm_memory invoked when the canister is low on main memory according to a new wasm_memory_threshold in canister settings.
• New system APIs ic0.cost_call, ic0.cost_create_canister, ic0.cost_http_request, ic0.cost_sign_with_ecdsa, ic0.cost_sign_with_schnorr, and ic0.cost_vetkd_derive_encrypted_key for cycles cost calculation.
• New field memory_metrics providing detailed metrics on the memory consumption of a canister in the response of the management canister's canister_status endpoint.

0.33.0 (2025-02-12) {#0_33_0}

• New system API ic0.subnet_self_size and ic0.subnet_self_copy.

0.32.0 (2025-01-23) {#0_32_0}

• Allow accepting and burning cycles in replicated queries.

0.31.0 (2025-01-09) {#0_31_0}

• Add support for Schnorr auxiliary inputs

0.30.0 (2024-11-19) {#0_30_0}

• Add management canister endpoint subnet_info.
• Support for wasm64: 64-bit system API.

0.29.0 (2024-11-14) {#0_29_0}

• Allow anonymous query and read state requests with invalid ingress_expiry.
• Add allowed viewers variant to canister log visibility.
• Deprecate the Bitcoin API of the management canister.

0.28.0 (2024-10-11) {#0_28_0}

• Add new management canister methods for canister snapshot support.

0.27.0 (2024-09-20) {#0_27_0}

• EXPERIMENTAL: Management canister API to fetch Bitcoin block headers.
• Synchronous update call API at /api/v3/canister/.../call.

0.26.0 (2024-07-23) {#0_26_0}

• EXPERIMENTAL: Management canister API for threshold Schnorr signatures.

0.25.0 (2024-06-14) {#0_25_0}

• Query call statistics.
• New wasm_memory_persistence option for canister upgrades.
• Rename num_blocks_total to num_blocks_proposed_total in node metrics served by the management canister.
• Management canister query call to fetch canister logs.
• WASM heap memory limit in canisters settings.
• 32-bit stable memory System API is marked DEPRECATED.
• Remove the management canister query calls bitcoin_get_balance_query and bitcoin_get_utxos_query.

0.24.0 (2024-04-23) {#0_24_0}

• Wrap chunk hash for install chunked code in a record and rename storage_canister to store_canister.
• Update subnet read state request conditions on requested paths.
• Fix: allow inter-canister calls (requests) to be spontaneously rejected in the abstract spec.

0.23.0 (2024-03-06) {#0_23_0}

• The maximum length of a nonce in an ingress message is 32 bytes.
• Update specification of responses from the endpoint /api/v2/status.
• Stop canister calls might be rejected upon timeout.
• The IC sends a user-agent header with the value ic/1.0 in canister HTTPS outcalls if the canister does not provide one.
• Add a management canister method for retrieving node metrics.
• Specify the resource reservation mechanism.
• Allow in_replicated_execution system API method to be executed during canister_start.
• Set the maximum depth of a delegation in a read_state response/certified variable certificate to 1.
• Canister version is guaranteed to increase if the canister's running status changes.
• Calls to frozen canisters are rejected with SYS_TRANSIENT instead of CANISTER_ERROR.
• Add API boundary nodes information into the certified state tree.

0.22.0 (2023-11-15) {#0_22_0}

• Add metrics on subnet usage into the certified state tree and a new HTTP endpoint /api/v2/subnet/<subnet_id>/read_state for retrieving them.
• Add management canister methods to support installing large WebAssembly modules split into chunks.
• Add a system API method to determine if the canister is running in replicated or non-replicated mode.
• Add a system API method to burn cycles of the canister that calls this method.
• Add a check that a canister receiving an ingress message is Running before the ingress message is marked as Received.
• Increase the maximum number of globals in a canister's WASM.
• Add per-call context performance counter.
• Update the computation of the representation-independent hash for the case of maps with nested maps.
• Remove senders field from user delegations.

0.21.0 (2023-09-18) {#0_21_0}

• Canister cycle balance cannot decrease below the freezing limit after executing install_code on the management canister.
• System API calls ic0.msg_caller_size and ic0.msg_caller_copy can be called in all contexts except for (start) function.
• Added note on confidentiality of values in the certified state tree.
• Update algorithm computing the request and response hash in the HTTP Gateway including clarification of when the HTTP Gateway can allow for arbitrary certification version in the canister's response.
• Update conditions on requested paths in HTTP read state requests.
• Added new query methods in the Bitcoin API.
• Added node public keys to certified state and node signatures to query call responses.
• Added a new mode for canister upgrades skipping pre-upgrade method's execution.

0.20.0 (2023-07-11) {#0_20_0}

• IC Bitcoin API, ECDSA API, canister HTTPS outcalls API, and 128-bit cycles System API are considered stable.
• Add conditions on requested paths in read state requests.
• Add composite queries.
• Specify that the canister version is incremented upon every successful message execution except for successful message execution of a query method.

0.19.0 (2023-06-08) {#0_19_0}

• canister version can be specified in some management canister calls (canister creation, canister code changes, canister settings changes)
• IC records canister history (canister creation, canister code changes, and canister controllers changes)
• added a new canister_info management canister call returning current module hash, current controllers, and canister history
• added a new system API call ic0.is_controller (checking if a principal is a controller of the canister)
• stable memory System API calls can be invoked in the WebAssembly module (start) function
• the system API call ic0.global_timer_set can be invoked in canister pre-upgrade
• added modeling WASM start function in the concrete CanisterModule specification
• WebAssembly module requirements have been revised (relaxed max number of declared functions and globals, added conditions on exported functions)
• certified variables are cleared if a canister is reinstalled
• a canister having an open call context marked as deleted cannot reach Stopped state
• a desired canister ID of the canister created by provisional_create_canister_with_cycles (in testing environments) can be specified using specified_id
• conditions on envelope delegations have been revised (relaxed max number of delegations, restricted max number of targets per delegation, forbidden cycles in the delegation chain)
• added a new optional field senders in envelope delegations (restricting users to which a delegation applies)
• all /request_status/<request_id> paths must refer to the same request_id in a read_state request
• IC protocol execution error conditions (such as failing inspect_message method of a canister) are returned as 200 HTTP responses with a cbor body describing the error (instead of 4xx or 5xx HTTP responses)

0.18.9 (2022-12-06) {#0_18_9}

• Global timers
• Canister version
• Clarifications for HTTP requests & Bitcoin integration costs

0.18.8 (2022-11-09) {#0_18_8}

• Updated HTTP request API
• Canister status available to canister
• 64-bit stable memory is no longer experimental

0.18.7 (2022-09-27) {#0_18_7}

• HTTP request API
• Reserved principals

0.18.6 (2022-08-09) {#0_18_6}

• Canister access to performance metrics
• Query calls are rejected when the canister is frozen
• Support for implementation-specific error codes for requests
• Deleted call contexts do not prevent canister from reaching Stopped state
• Update effective canister id checks in certificate delegations
• Formal model in Isabelle

0.18.5 (2022-07-08) {#0_18_5}

• Idle consumption of resources in cycles per day can be obtain via canister_status method of the management canister
• Include the HTTP Gateway Protocol in this spec
• Clarifications in definition of cycles consumption

0.18.4 (2022-06-20) {#0_18_4}

• Canister cycle balances are represented by 128 bits, and no system-defined upper limit exists anymore
• Canister modules can be gzip-encoded
• Expose Wasm custom sections in the state tree
• EXPERIMENTAL: Canister API for accessing Bitcoin transactions
• EXPERIMENTAL: Canister API for threshold ECDSA signatures

0.18.3 (2022-01-10) {#0_18_3}

• New System API which uses 128-bit values to represent the amount of cycles
• Subnet delegations include a canister id scope

0.18.2 (2021-09-29) {#0_18_2}

• Canister heartbeat
• Terminology changes
• Support for 64-bit stable memory

0.18.1 (2021-08-04) {#0_18_1}

• Support RSA PKCS#1 v1.5 signatures in web authentication
• Spec clarification: Fix various typos and improve textual clarity

0.18.0 (2021-05-18) {#0_18_0}

• A canister has a set of controllers, instead of always one

0.17.0 (2021-04-22) {#0_17_0}

• Canister Signatures are introduced
• Spec clarification: the signature in the WebAuthn scheme is prefixed by the CBOR self-identifying tag
• Cycle-depleted canisters are forcibly uninstalled
• Canister settings in create_canister and update_settings. install_code no longer takes allocation settings.
• A freezing threshold can be configured via the canister settings

0.16.1 (2021-04-14) {#0_16_1}

• The cleanup callback is introduced

0.16.0 (2021-03-25) {#0_16_0}

• New http v2 API that allows for stateless boundary nodes

0.15.6 (2021-03-25) {#0_15_6}

• The system may impose limits on the number of globals and functions
• No ingress messages towards empty canisters are accepted
• No ingress messages towards raw_rand and deposit_cycles are accepted
• A memory allocation of 0 means “best effort”

0.15.5 (2021-03-11) {#0_15_5}

• deposit_cycles(): any caller allowed

0.15.4 (2021-03-04) {#0_15_4}

• Ingress message filtering
• Add ECDSA signatures on curve secp256k1
• Clarify that the ic0.data_certificate_present system function may be called in all contexts.

0.15.3 (2021-02-26) {#0_15_3}

• Expose module hash and controller via read_state

0.15.2 (2021-02-09) {#0_15_2}

• The document is renamed to “Internet Computer Interface Spec”

0.15.0 (2020-12-17) {#0_15_0}

• Support for raw Ed25519 keys is removed

0.14.1 (2020-12-08) {#0_14_1}

• The default memory_allocation becomes unspecified

0.14.0 (2020-11-18) {#0_14_0}

• Support for funds is scaled back to only support cycles
• The ic0.msg_cycles_accept system call now returns the actually accepted cycles
• The provisional_ management calls are introduced

0.13.2 (2020-11-12) {#0_13_2}

• The ic0.canister_status system call

0.13.1 (2020-11-06) {#0_13_1}

• Delegation between user public keys

0.13.0 (2020-10-19) {#0_13_0}

• Certification (also removes “request-status” request)

0.12.2 (2020-10-23) {#0_12_2}

• User authentication method based on WebAuthn is introduced
• User authentication can use ECDSA
• Public keys are DER-encoded

0.12.1 (2020-10-16) {#0_12_1}

• Return more information in the canister_status management call

0.12.0 (2020-10-13) {#0_12_0}

• Anonymous requests must have the sender field set

0.11.1 (2020-10-01) {#0_11_1}

• The deposit_funds call

0.11.0 (2020-09-23) {#0_11_0}

• Inter-canister calls are now performed using a builder-like API
• Support for funds (balances and transfers)

0.10.3 (2020-09-21) {#v0_10_3}

• The anonymous user is introduced

0.10.1 (2020-09-01) {#v0_10_1}

• Forward-port changes from 0.9.3

0.10.0 (2020-08-06) {#v0_10_0}

• Users can set/update a memory allocation when installing/upgrading a canister.
• The expiry field is added to requests

0.9.3 (2020-09-01) {#v0_9_3}

• The management canister supports the raw_rand method

0.9.2 (2020-08-05) {#v0_9_2}

• Canister controllers can stop/start canisters and can query their status.
• Canister controllers can delete canisters

0.9.1 (2020-07-20) {#v0_9_1}

• Forward-port changes from 0.8.2

0.9.0 (2020-07-15) {#v0_9_0}

• Introduction of a domain separator (again)
• The calculation of “derived ids” has changed
• The self-authenticating and derived id forms use a truncated hash
• The textual representation of principals has changed

0.8.2 (2020-07-17) {#v0_8_2}

• Installing code via reinstall works also on the empty canister

0.8.1 (2020-07-10) {#v0_8_1}

• Reflect refined process in README and intro.
• ic0.time added

0.8.0 (2020-06-23) {#v0_8_0}

• Revert the introduction of a domain separator

0.6.2 (2020-06-23) {#v0_6_2}

• Fix meaning-changing typos in ic.did

0.6.0 (2020-06-08) {#v0_6_0}

• Make all canister ids system-chosen
• HTTP requests for management features are removed

0.4.0 (2020-05-25) {#v0_4_0}

• (editorial) the term “principal” is now used for the id of a canister or user, not the canister or user itself
• The signature of a request needs to be calculated using a domain separator
• Describe the controller attribute, add a request to change it
• The IC management canister is introduced

0.2.16 (2020-05-29) {#v0_2_16}

• More tests about calls from query methods

0.2.14 (2020-05-14) {#v0_2_14}

• Bugfix: Mode should be reinstall, not replace

0.2.8 (2020-04-23) {#v0_2_8}

• Include section with CDDL description

0.2.4 (2020-03-23) {#v0_2_4}

• simplify versioning (only three components), skip 0.2.2 to avoid confusion with 0.2.0.2
• Clarification: reply field is always present
• General cleanup based on front-to-back reading

0.2.0.0 (2020-03-11) {#v0_2_0_0}

• This is the first release. Subsequent releases will include a changelog.