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.
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_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 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 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.