Object of type DockerMount is not JSON serializable #6469
Description
Describe the issue you are experiencing
Multiple people are reporting that a recent Supervisor update has broken their HA installation.
See #6474 and https://community.home-assistant.io/t/update-to-2026-1-0-and-ui-no-longer-loads/971893
I think this was introduced in d23bc29
What type of installation are you running?
Home Assistant OS
Which operating system are you running on?
Home Assistant Operating System
Steps to reproduce the issue
- Install or Update to the latest version.
- HA won't load
ha core checkreturnsError: Object of type DockerMount is not JSON serializable
See #6474 (comment)
Anything in the Supervisor logs that might be useful for us?
2026-01-10 10:47:06.058 INFO (SyncWorker_5) [supervisor.docker.manager] Runing command 'python3 -m homeassistant -c /config --script check_config' on ghcr.io/home-assistant/qemux86-64-homeassistant:2025.10.4
2026-01-10 10:47:06.059 ERROR (MainThread) [supervisor.jobs] Unhandled exception: Object of type DockerMount is not JSON serializable
Traceback (most recent call last):
File "/usr/src/supervisor/supervisor/jobs/decorator.py", line 299, in wrapper
return await method(obj, *args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/src/supervisor/supervisor/docker/homeassistant.py", line 215, in execute_command
return await self.sys_run_in_executor(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...<28 lines>...
)
^
File "/usr/local/lib/python3.13/concurrent/futures/thread.py", line 59, in run
result = self.fn(*self.args, **self.kwargs)
File "/usr/src/supervisor/supervisor/docker/manager.py", line 638, in run_command
container = self.dockerpy.containers.run(
image_with_tag,
...<4 lines>...
**kwargs,
)
File "/usr/local/lib/python3.13/site-packages/docker/models/containers.py", line 876, in run
container = self.create(image=image, command=command,
detach=detach, **kwargs)
File "/usr/local/lib/python3.13/site-packages/docker/models/containers.py", line 935, in create
resp = self.client.api.create_container(**create_kwargs)
File "/usr/local/lib/python3.13/site-packages/docker/api/container.py", line 440, in create_container
return self.create_container_from_config(config, name, platform)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.13/site-packages/docker/api/container.py", line 456, in create_container_from_config
res = self._post_json(u, data=config, params=params)
File "/usr/local/lib/python3.13/site-packages/docker/api/client.py", line 303, in _post_json
return self._post(url, data=json.dumps(data2), **kwargs)
~~~~~~~~~~^^^^^^^
File "/usr/local/lib/python3.13/json/__init__.py", line 235, in dumps
return _default_encoder.encode(obj)
~~~~~~~~~~~~~~~~~~~~~~~^^^^^
File "/usr/local/lib/python3.13/json/encoder.py", line 202, in encode
chunks = self.iterencode(o, _one_shot=True)
File "/usr/local/lib/python3.13/json/encoder.py", line 263, in iterencode
return _iterencode(o, 0)
File "/usr/local/lib/python3.13/json/encoder.py", line 182, in default
raise TypeError(f'Object of type {o.__class__.__name__} '
f'is not JSON serializable')
TypeError: Object of type DockerMount is not JSON serializableSystem information
arch: amd64
audio_input: null
audio_output: null
backups_exclude_database: false
boot: true
duplicate_log_file: false
image: ghcr.io/home-assistant/qemux86-64-homeassistant
ip_address: 172.30.32.1
machine: qemux86-64
port: 8123
ssl: true
update_available: true
version: 2025.10.4
version_latest: 2026.1.0
watchdog: true
Supervisor diagnostics
No response
Additional information
No response