The ten deprecated ClimateTraits::get/set_supports_* accessors have been removed. External climate components must migrate to the add_feature_flags() / has_feature_flags() API introduced in 2025.11.0 — the 6-month deprecation window has elapsed.
This is a breaking change for external components in ESPHome 2026.5.0 and later.
The no-argument PollingComponent() constructor now initializes the update interval to SCHEDULER_DONT_RUN (UINT32_MAX) instead of 1. External components that subclass PollingComponent, instantiate it with no constructor argument, and never call set_update_interval() will stop polling. Pass an interval to the constructor or call set_update_interval() explicitly.
This is a breaking change for external components in ESPHome 2026.5.0 and later.
The min_power_ / max_power_ / zero_means_zero_ fields and their setters on FloatOutput are now gated behind a new USE_OUTPUT_FLOAT_POWER_SCALING build flag. The codegen turns the flag on automatically whenever a YAML config references the feature. Lambdas that call id(out).set_min_power(...) / set_max_power(...) / set_zero_means_zero(...) without any matching YAML key or action will now fail to compile with a clear static_assert pointing at the one-line YAML fix.
This is a breaking change for external components and YAML configs that drive power scaling exclusively from lambdas in ESPHome 2026.5.0 and later.
Every component’s loop() now runs at the configured loop_interval_ (default ~62 Hz). Previously, when other scheduler activity was running — set_interval / set_timeout / PollingComponent updates with sub-loop_interval_ cadences — the component phase got pulled forward up to ~128 Hz; quiet configs with no such scheduler entries were unaffected and always ran at the documented rate. Background events (MQTT RX, USB RX, BLE events, ESPNOW, camera, micro_wake_word, speaker, USB host/CDC, lwIP socket) still wake their component within one tick via the existing wake_loop_* paths. App.set_loop_interval() — the documented knob for power savings — finally works.
This is a behavior change in ESPHome 2026.5.0 and later with no API break, but it affects every component whose loop() implicitly depended on running at ~2× the configured rate when scheduler activity was driving the pull-forward.
Modbus server mode has been split out of modbus_controller into a new dedicated modbus_server component. Configurations that used modbus_controller as a Modbus server (the role: server setting lives on the modbus: bus, not on modbus_controller) must move their server_registers: and server_courtesy_response: blocks under a new top-level modbus_server: entry.
This is a breaking change for YAML configurations using server mode in ESPHome 2026.5.0 and later.
RingBuffer has moved from esphome/core/ring_buffer.h into a new ring_buffer helper component at esphome/components/ring_buffer/ring_buffer.h under the esphome::ring_buffer namespace. The old location is deprecated and will be removed in ESPHome 2026.11.0.
This is a breaking change for external components in ESPHome 2026.5.0 and later.
Virtual handler interfaces (GAPEventHandler, GAPScanEventHandler, GATTcEventHandler, GATTsEventHandler, BLEStatusEventHandler) have been replaced with callback-based dispatch. External components that inherit from these interfaces must update their registration approach.
This is a developer breaking change for external components in ESPHome 2026.4.0 and later.
CallbackManager and LazyCallbackManager now use a lightweight 8-byte Callback struct instead of std::function (16 bytes). External components that define their own callback registration methods using std::function should update to templates for optimal performance.
This is a breaking change for external components in ESPHome 2026.4.0 and later.
Custom mode vectors (custom_fan_modes, custom_presets for climate; preset_modes for fan) are now stored on the entity base class instead of being rebuilt inside traits on every call. The old ClimateTraits and FanTraits setter methods are deprecated.
This is a breaking change for external components in ESPHome 2026.4.0 and later.
The FlushResult enum introduced in ESPHome 2026.3.0 has been renamed to UARTFlushResult with prefixed enum values to follow ESPHome’s naming conventions and avoid macro collisions.
This is a breaking change for external components in ESPHome 2026.4.0 and later.
Shared helper functions and types have been moved from modbus_controller to modbus::helpers to enable reuse by other modbus-based components. Deprecated shims keep the old names working until ESPHome 2026.10.0.
This is a developer breaking change for external components in ESPHome 2026.4.0 and later.
Direct access to the sensor .raw_state member is now deprecated. Use get_raw_state() instead. The .raw_state member will be removed in ESPHome 2026.10.0.
This is a breaking change for external components in ESPHome 2026.4.0 and later.
The TEMPLATABLE_VALUE macro now uses TemplatableFn (4 bytes) instead of TemplatableValue (8 bytes) for trivially copyable types like float, uint32_t, bool, and enums. External components that call macro-generated setters with raw C++ constants instead of going through cg.templatable() will fail to compile.
This is a breaking change for external components in ESPHome 2026.4.0 and later.
Common entity trigger classes have been replaced with lightweight forwarder structs that fit inline in the callback system. The new build_callback_automation() API eliminates per-trigger object allocations. Several entity callback signatures have also changed to pass state as an argument.
This is a breaking change for external components in ESPHome 2026.4.0 and later.
wake_loop_threadsafe() and related wake primitives have moved from the socket component into core. The require_wake_loop_threadsafe() opt-in is deprecated (now a no-op) — wake works unconditionally on all platforms.
This is a breaking change for external components in ESPHome 2026.4.0 and later.
App.get_name() and App.get_friendly_name() now return const StringRef & instead of const std::string &. Most code compiles unchanged because StringRef provides .c_str(), .size(), .empty(), and implicit conversion to std::string. However, binding the result to const std::string & silently creates a heap-allocated temporary — update these references to const auto & to avoid the allocation.
This is a breaking change for external components in ESPHome 2026.3.0 and later.
Component::call_loop(), Component::mark_failed(), and Component::call_dump_config() are no longer virtual methods. External components that override any of these methods must remove them entirely and move logic to loop() or dump_config(). This saves 800+ bytes of flash globally from vtable elimination.
This is a breaking change for external components in ESPHome 2026.3.0 and later.
The get_loop_priority() virtual method on Component is now only available when USE_LOOP_PRIORITY is defined. This define is only set on RP2040, the only platform where loop priority has an effect. External components that override get_loop_priority() must guard the override with #ifdef USE_LOOP_PRIORITY.
This is a breaking change for external components in ESPHome 2026.3.0 and later.
The http_request component’s C++ API has been updated to use std::vector instead of std::map, std::list, and std::set for header handling. The get_response_headers() method (returning the full headers map) has been removed — use get_response_header(name) instead. Deprecated overloads using the old container types are provided until 2027.1.0.
This is a breaking change for external components in ESPHome 2026.3.0 and later.
The get_icon_ref(), get_icon(), get_device_class_ref(), and get_device_class() methods are deprecated on all platforms and replaced by new buffer-based APIs get_icon_to() and get_device_class_to(). On ESP8266, the old methods produce a static_assert error because the underlying strings have been moved to PROGMEM and cannot be accessed through normal C string pointers. On other platforms, the old methods continue to work but emit deprecation warnings and will be removed in 2026.9.0.
This is a breaking change for external components in ESPHome 2026.3.0 and later.
The logger::LogListener abstract class has been removed. Components that receive log messages must now register a callback with logger::global_logger->add_log_callback(instance, callback) instead of inheriting from LogListener and calling add_log_listener().
This is a breaking change for external components in ESPHome 2026.3.0 and later.
All register_action() calls now require an explicit synchronous=True or synchronous=False parameter. This enables the StringRef optimization for synchronous actions (zero-copy string argument passing) while ensuring asynchronous actions safely use owning std::string to prevent dangling references. Existing external components will continue to work but will see a warning at config time until updated.
This is a breaking change for external components in ESPHome 2026.3.0 and later.
The RP2040 platform has been updated to arduino-pico 5.5.0 (from 3.9.4), pico-sdk 2.1.0 (from 1.5.1), and GCC 14 (from GCC 12). Several hardware register names, API functions, and macros have changed. External components targeting RP2040 may need updates.
This is a breaking change for external components in ESPHome 2026.3.0 and later.
The socket::Socket and socket::ListenSocket types have been changed from virtual base classes to concrete type aliases. Listen sockets now use the ListenSocket type instead of Socket. These changes save 1,020–3,228 bytes of flash across platforms by eliminating virtual dispatch overhead.
This is a breaking change for external components in ESPHome 2026.3.0 and later.
The UARTComponent::flush() method return type has changed from void to FlushResult. External components that subclass UARTComponent and override flush() must update their override to return a FlushResult value.
This is a breaking change for external components in ESPHome 2026.3.0 and later.
ESP32 builds now exclude unused built-in IDF components by default to reduce compile time. This applies to both ESP-IDF and Arduino framework builds, since both use the ESP-IDF build system underneath. External components that use excluded IDF APIs (e.g., esp_vfs_fat.h, esp_http_client.h, esp_eth.h) must explicitly re-enable them via include_builtin_idf_component().
This is a breaking change for external components in ESPHome 2026.2.0 and later.
get_preference_hash() is deprecated. Use the new make_entity_preference<T>() method to create preference objects for storing entity state. This prepares for fixing preference hash collisions that cause entities to overwrite each other’s stored data.
This is a breaking change for external components in ESPHome 2026.2.0 and later.
ESP32 Arduino builds now disable all Arduino libraries by default. ESPHome uses ESP-IDF APIs directly for WiFi, networking, and BLE, so most Arduino libraries were compiled and linked but never called. External components that use Arduino libraries must explicitly enable them via cg.add_library().
This is a breaking change for external components in ESPHome 2026.2.0 and later.
The set_retry, cancel_retry, and RetryResult APIs are deprecated. They will be removed in ESPHome 2026.8.0. Use set_timeout or set_interval instead.
This is a breaking change for external components in ESPHome 2026.2.0 and later.
WiFi and Logger components now use StaticVector for listener storage, eliminating heap allocation and STL overhead. External components that register listeners must now call request functions during code generation.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
The scheduler’s std::string-based APIs (set_timeout, set_interval, set_retry, defer, and their cancel counterparts) are now deprecated. Use const char* string literals or uint32_t numeric IDs instead.
This deprecation affects ESPHome 2026.1.0 and later, with removal planned for 2026.7.0.
The App.get_compilation_time() method is deprecated in favor of new constexpr methods. The compilation_time field in the native API now updates on every compile.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
The callback signatures for text_sensor, text, and select components have been updated to reduce heap allocations. The select component callback signature has changed significantly.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
Several entity component getters now return StringRef instead of const char* or std::string. This improves safety by eliminating null pointer crashes and provides a modern C++ API.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
ESP8266 builds now exclude unused Serial objects and waveform/PWM code by default. External components using these features must explicitly enable them.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
The GPIOPin::dump_summary() virtual method now writes to a caller-provided buffer instead of returning std::string. This eliminates heap allocations during configuration dumps.
This is a breaking change for external components that implement custom GPIO pins in ESPHome 2026.1.0 and later.
The OTA component now uses a listener interface instead of std::function callbacks. The alarm control panel component has removed per-state callback methods in favor of a unified state callback.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
The Socket class virtual methods getpeername() and getsockname() that returned std::string have been removed. The ClientInfo struct no longer contains std::string fields.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
Several string formatting helpers that returned std::string are now soft-deprecated in favor of stack-based alternatives. This prevents heap fragmentation on long-running ESP devices.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
The USE_ESP_IDF C++ define and related Python APIs are deprecated. Since Arduino-ESP32 is built on ESP-IDF, all IDF APIs are available on ESP32 regardless of framework selection.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
The light component’s callback system has been refactored to use a listener interface pattern with lazy allocation. This replaces the previous CallbackManager<void()> approach with explicit listener interfaces that only allocate memory when callbacks are actually registered.
This is a breaking change for external components that register light state callbacks in ESPHome 2025.12.0 and later.
The network::get_use_address() function has been optimized to return const char* instead of const std::string& to reduce memory overhead. This eliminates unnecessary string object storage when accessing the device’s network address.
This is a breaking change for external components that call network::get_use_address() in ESPHome 2025.11.0 and later.
ESPHome 2025.11.0 introduces significant memory optimizations to the Climate entity class that affect external components implementing custom climate devices.
ESPHome 2025.11.0 introduces memory optimizations to the Event entity class that reduce heap usage and store event type strings in flash. These changes affect external components implementing custom event devices.
ESPHome 2025.11.0 introduces a memory optimization to the Fan entity class that also changes how preset modes are ordered. This affects external components implementing custom fan devices and may change the display order of preset modes in Home Assistant.
ESPHome 2025.11.0 introduces memory optimizations to the Light entity class that reduce both heap and flash usage. These changes affect external components implementing custom light devices and effects.
ESPHome 2025.11.0 introduces significant optimizations to the Select entity class that reduce memory usage and improve performance. These changes affect external components that implement custom select entities.
The core automation framework (actions, triggers, and conditions) has been optimized to use const references instead of pass-by-value for parameter passing. This reduces memory allocations by 83% in the automation execution path.
This is a breaking change for external components with custom actions or conditions in ESPHome 2025.11.0 and later.
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