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.
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