Core update to 2026.1.0 broke my bms_connector . would not load

[Irishrossy]

BMS Version 🔄

1.0.5

Connection Method 🌐

USB-RS485

Pre-submission Checklist ✅

• This issue is focused on a single problem (For multiple issues, create separate reports).
• I've checked for existing issues and confirmed mine is unique.

What's happening? 🤔

Last update of Home Assistant in Jan 2026 broke my bms_connector to Seplos bms , I was able to get Chatgpt to help me with Pyton as i,m not a super user ....

Changes made to 2 files ..."sensor.py" cause its — 2026.1.0 will break that sensor.py as-written because it’s still using removed/deprecated typing aliases.

Heres what chat gpt gave me

import logging

from homeassistant.core import HomeAssistant
from homeassistant.config_entries import ConfigEntry
from homeassistant.helpers.entity_platform import AddEntitiesCallback

#################################################
############## BMS Routing Imports ##############
#################################################
from .bms.seplos.v2.sensors import generate_sensors as SEPLOS_V2_START
from .bms.seplos.v3.sensors import generate_sensors as SEPLOS_V3_START

_LOGGER = logging.getLogger(name)

async def async_setup_entry(
hass: HomeAssistant,
config_entry: ConfigEntry,
async_add_entities: AddEntitiesCallback,
) -> None:
"""Set up sensors from a config entry."""
try:
sensor_prefix = config_entry.data.get("sensor_prefix")
bms_type = config_entry.data.get("bms_type")
port = config_entry.data.get("connector_port")
battery_address = config_entry.data.get("battery_address")
entry = config_entry.data

    _LOGGER.debug("Sensor Prefix: %s", sensor_prefix)
    _LOGGER.debug("BMS Type: %s", bms_type)
    _LOGGER.debug("Port: %s", port)
    _LOGGER.debug("Battery Address: %s", battery_address)

    # For SEPLV2 BMS's
    if bms_type == "SEPLV2":
        _LOGGER.debug("%s selected. Routing now..", bms_type)
        await SEPLOS_V2_START(
            hass, bms_type, port, battery_address, sensor_prefix, entry, async_add_entities
        )

    # For SEPLV3 BMS's
    elif bms_type == "SEPLV3":

And
_LOGGER.debug("%s selected. Routing now..", bms_type)
await SEPLOS_V3_START(
hass, bms_type, port, battery_address, sensor_prefix, entry, async_add_entities
)

    else:
        _LOGGER.error("Unsupported BMS type: %s", bms_type)

except Exception as e:
    _LOGGER.exception("Error setting up BMS sensors: %s", e)

......Second file was "init.py"

That traceback is very clear: your init.py is trying to import a function that does not exist anymore.

from .sensor import initialize_bms_component
ImportError: cannot import name 'initialize_bms_component'

So i replaced with

from future import annotations

from homeassistant.core import HomeAssistant
from homeassistant.config_entries import ConfigEntry

PLATFORMS: list[str] = ["sensor"]

async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
"""Set up bms_connector from a config entry."""
await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)
return True

async def async_unload_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
"""Unload a config entry."""
return await hass.config_entries.async_unload_platforms(entry, PLATFORMS)

All working now i have uploaded new files to this chat

Steps to Reproduce 🔍

init.py

sensor.py

...

Debug logs 📜

Logger: homeassistant.setup
Source: setup.py:343
First occurred: 14:04:21 (1 occurrence)
Last logged: 14:04:21

Setup failed for custom integration 'bms_connector': Unable to import component: cannot import name 'initialize_bms_component' from 'custom_components.bms_connector.sensor' (/config/custom_components/bms_connector/sensor.py)
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/loader.py", line 1018, in async_get_component
    comp = await self.hass.async_add_import_executor_job(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        self._get_component, True
        ^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/usr/local/lib/python3.13/concurrent/futures/thread.py", line 59, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/src/homeassistant/homeassistant/loader.py", line 1078, in _get_component
    ComponentProtocol, importlib.import_module(self.pkg_path)
                       ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/util/loop.py", line 201, in protected_loop_func
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.13/importlib/__init__.py", line 88, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1387, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 1023, in exec_module
  File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed
  File "/config/custom_components/bms_connector/__init__.py", line 9, in <module>
    from .sensor import initialize_bms_component
ImportError: cannot import name 'initialize_bms_component' from 'custom_components.bms_connector.sensor' (/config/custom_components/bms_connector/sensor.py)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/setup.py", line 343, in _async_setup_component
    component = await integration.async_get_component()
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/loader.py", line 1038, in async_get_component
    self._component_future.result()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/usr/src/homeassistant/homeassistant/loader.py", line 1030, in async_get_component
    comp = self._get_component()
  File "/usr/src/homeassistant/homeassistant/loader.py", line 1078, in _get_component
    ComponentProtocol, importlib.import_module(self.pkg_path)
                       ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/util/loop.py", line 201, in protected_loop_func
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.13/importlib/__init__.py", line 88, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1387, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 1023, in exec_module
  File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed
  File "/config/custom_components/bms_connector/__init__.py", line 9, in <module>
    from .sensor import initialize_bms_component
ImportError: cannot import name 'initialize_bms_component' from 'custom_components.bms_connector.sensor' (/config/custom_components/bms_connector/sensor.py)

Diagnostics dump 📦

No response

[TheMiniBar]

I have the same issue after the last core update but not sure I can understand your fix. Is there a chance a future core update will resolve this for me?

[Ciuffo79]

#I solved it by modifying the "custom_components/bms_connector/sensor.py" file with the following code:

import logging

from homeassistant.core import HomeAssistant
from homeassistant.config_entries import ConfigEntry
from homeassistant.helpers.entity_platform import AddEntitiesCallback

#################################################
############## BMS Routing Imports ##############
#################################################
from .bms.seplos.v2.sensors import generate_sensors as SEPLOS_V2_START
from .bms.seplos.v3.sensors import generate_sensors as SEPLOS_V3_START

_LOGGER = logging.getLogger(name)

async def initialize_bms_component(hass: HomeAssistant, config_entry: ConfigEntry) -> None:
"""
Kept for backward-compatibility: init.py imports this symbol.
If the integration doesn't use it anymore, it can remain as a no-op.
"""
return

async def async_setup_entry(
hass: HomeAssistant,
config_entry: ConfigEntry,
async_add_entities: AddEntitiesCallback,
) -> None:
"""Set up sensors from a config entry."""
try:
sensor_prefix = config_entry.data.get("sensor_prefix")
bms_type = config_entry.data.get("bms_type")
port = config_entry.data.get("connector_port")
battery_address = config_entry.data.get("battery_address")
entry = config_entry.data

    _LOGGER.debug("Sensor Prefix: %s", sensor_prefix)
    _LOGGER.debug("BMS Type: %s", bms_type)
    _LOGGER.debug("Port: %s", port)
    _LOGGER.debug("Battery Address: %s", battery_address)

    # For SEPLV2 BMS's
    if bms_type == "SEPLV2":
        _LOGGER.debug("%s selected. Routing now..", bms_type)
        await SEPLOS_V2_START(
            hass, bms_type, port, battery_address, sensor_prefix, entry, async_add_entities
        )

    # For SEPLV3 BMS's
    elif bms_type == "SEPLV3":
        _LOGGER.debug("%s selected. Routing now..", bms_type)
        await SEPLOS_V3_START(
            hass, bms_type, port, battery_address, sensor_prefix, entry, async_add_entities
        )

    else:
        _LOGGER.error("Unsupported BMS type: %s", bms_type)

except Exception as err:
    _LOGGER.exception("Error setting up BMS sensors: %s", err)

[TheMiniBar]

I asked MS Co-Pilot to look at the code above. It reported the following back to me.

Change:
(logging.getLogger(name)
to:
logging.getLogger(name)).

I applied the recommended change and now my BMS integration is working again.