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.
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.
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.