Unable to stop charging

[tux43]

Describe the bug
When the OCPP charger is charging and I switch off the switch.charger_charge_control it does not stop charging and throws an error.

To Reproduce
Steps to reproduce the behavior:
Set the switch.charger_charge_control from on to off for Sigen EVDC charger

Expected behavior
Charging to stop

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
Error log

2025-11-13 09:20:30.359 INFO (MainThread) [ocpp] 110A42BL0102: receive message [2,"4688","StopTransaction",{"meterStop":250390,"timestamp":"2025-11-10T10:23:58Z","transactionId":1762770182,"idTag":"X16WG99J2QIEGCC0MCJ5-"}]
2025-11-13 09:20:30.360 ERROR (MainThread) [ocpp] Error while handling request '<Call - unique_id=4688, action=StopTransaction, payload={'meterStop': 250390, 'timestamp': '2025-11-10T10:23:58Z', 'transactionId': 1762770182, 'idTag': 'X16WG99J2QIEGCC0MCJ5-'}>'
Traceback (most recent call last):
File "/usr/local/lib/python3.13/site-packages/ocpp/messages.py", line 240, in _validate_payload
validator.validate(message.payload)
~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.13/site-packages/jsonschema/validators.py", line 451, in validate
raise error
jsonschema.exceptions.ValidationError: 'X16WG99J2QIEGCC0MCJ5-' is too long

Failed validating 'maxLength' in schema['properties']['idTag']:
{'type': 'string', 'maxLength': 20}

On instance['idTag']:
'X16WG99J2QIEGCC0MCJ5-'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/usr/local/lib/python3.13/site-packages/ocpp/charge_point.py", line 272, in route_message
await self._handle_call(msg)
File "/config/custom_components/ocpp/chargepoint.py", line 532, in _handle_call
await super()._handle_call(msg)
File "/usr/local/lib/python3.13/site-packages/ocpp/charge_point.py", line 300, in _handle_call
await validate_payload(msg, self._ocpp_version)
File "/usr/local/lib/python3.13/site-packages/ocpp/messages.py", line 179, in validate_payload
await asyncio.get_event_loop().run_in_executor(
None, _validate_payload, message, ocpp_version
)
File "/usr/local/lib/python3.13/concurrent/futures/thread.py", line 59, in run
result = self.fn(*self.args, **self.kwargs)
File "/usr/local/lib/python3.13/site-packages/ocpp/messages.py", line 254, in _validate_payload
raise TypeConstraintViolationError(
details={"cause": e.message, "ocpp_message": message}
) from e
ocpp.exceptions.TypeConstraintViolationError: TypeConstraintViolationError: Payload for Action is syntactically correct but at least one of the fields violates data type constraints (e.g. “somestring”: 12), {'cause': "'X16WG99J2QIEGCC0MCJ5-' is too long", 'ocpp_message': <Call - unique_id=4688, action=StopTransaction, payload={'meterStop': 250390, 'timestamp': '2025-11-10T10:23:58Z', 'transactionId': 1762770182, 'idTag': 'X16WG99J2QIEGCC0MCJ5-'}>}
2025-11-13 09:20:30.365 INFO (MainThread) [ocpp] 110A42BL0102: send [4,"4688","TypeConstraintViolation","Payload for Action is syntactically correct but at least one of the fields violates data type constraints (e.g. \u201csomestring\u201d: 12)",{"cause":"'X16WG99J2QIEGCC0MCJ5-' is too long","ocpp_message":"[2,"4688","StopTransaction",{"meterStop":250390,"timestamp":"2025-11-10T10:23:58Z","transactionId":1762770182,"idTag":"X16WG99J2QIEGCC0MCJ5-"}]"}]

[gabbuman]

Hi,

The issue is caused by the idTag contained in the Stop Transaction payload violating the constraints laid out in the OCPP 1.6 protocol.

For some context: the idTag can be obtained either locally by the charger in most cases (reading some hardware token 4 or 7 bytes long) OR when the Central System sends charging commands to the Charge Point it may use: single use virtual transaction auth codes or virtual RFID tokens which deliverately use a non-standard UID format.

You are in the latter case.

The idTag is allowed to have any data as long as it is a string of 20 characters max length. The idTag used in the presented logs: X16WG99J2QIEGCC0MCJ5- is 21 characters and violates this constraint. Which is why the Stop Transaction is never sent to the charge point and the charging does not stop.

For Reference from official OCPP1.6 documentation:

My own investigation:

The idTag is an optional parameter and not including it may solve this symptom but does not solve the underlying problem. It is my first time going through the code base and I traced down the Central System parameter 'csid' (Central System ID) which I believe is used for the idTag parameter but I cannot determine the generation or configuration mechanism for this. The Central System is defined in ocpp/api.py file but I cannot find where this class is instantiated.

The generation/configuration must be constrained to a 20 character string to avoid this problem!

Hope this helps...

[gabbuman]

Right after I wrote this I ran into ocpp/config_flow.py where the csid is retrieved from user input!

The user input is validated by using https://github.com/alecthomas/voluptuous library and there is no max length provided for the csid parameter.

Setting a max length of 20 should fix this issue! Working on this!

[gabbuman]

PR regarding this issue: #1819

[gabbuman]

The PR is merged to allow max of 20 characters for the CSID input.

@tux43 please perform re-configure the Central System with the Central System Identity < 20 characters length and retry to confirm the diagnosis and fix!

Documentation at: https://home-assistant-ocpp.readthedocs.io/en/latest/user-guide.html

[tux43]

Thanks, I changed line 64 of config_flow.py however I still receive the same errors.

`2025-11-30 17:31:24.693 INFO (MainThread) [ocpp] 110A42BL0102: receive message [2,"4688","StopTransaction",{"meterStop":250390,"timestamp":"2025-11-10T10:23:58Z","transactionId":1762770182,"idTag":"X16WG99J2QIEGCC0MCJ5-"}]
2025-11-30 17:31:24.694 ERROR (MainThread) [ocpp] Error while handling request '<Call - unique_id=4688, action=StopTransaction, payload={'meterStop': 250390, 'timestamp': '2025-11-10T10:23:58Z', 'transactionId': 1762770182, 'idTag': 'X16WG99J2QIEGCC0MCJ5-'}>'
Traceback (most recent call last):
File "/usr/local/lib/python3.13/site-packages/ocpp/messages.py", line 240, in _validate_payload
validator.validate(message.payload)
~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.13/site-packages/jsonschema/validators.py", line 451, in validate
raise error
jsonschema.exceptions.ValidationError: 'X16WG99J2QIEGCC0MCJ5-' is too long

Failed validating 'maxLength' in schema['properties']['idTag']:
{'type': 'string', 'maxLength': 20}

On instance['idTag']:
'X16WG99J2QIEGCC0MCJ5-'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/usr/local/lib/python3.13/site-packages/ocpp/charge_point.py", line 272, in route_message
await self._handle_call(msg)
File "/config/custom_components/ocpp/chargepoint.py", line 532, in _handle_call
await super()._handle_call(msg)
File "/usr/local/lib/python3.13/site-packages/ocpp/charge_point.py", line 300, in _handle_call
await validate_payload(msg, self._ocpp_version)
File "/usr/local/lib/python3.13/site-packages/ocpp/messages.py", line 179, in validate_payload
await asyncio.get_event_loop().run_in_executor(
None, _validate_payload, message, ocpp_version
)
File "/usr/local/lib/python3.13/concurrent/futures/thread.py", line 59, in run
result = self.fn(*self.args, **self.kwargs)
File "/usr/local/lib/python3.13/site-packages/ocpp/messages.py", line 254, in _validate_payload
raise TypeConstraintViolationError(
details={"cause": e.message, "ocpp_message": message}
) from e
ocpp.exceptions.TypeConstraintViolationError: TypeConstraintViolationError: Payload for Action is syntactically correct but at least one of the fields violates data type constraints (e.g. “somestring”: 12), {'cause': "'X16WG99J2QIEGCC0MCJ5-' is too long", 'ocpp_message': <Call - unique_id=4688, action=StopTransaction, payload={'meterStop': 250390, 'timestamp': '2025-11-10T10:23:58Z', 'transactionId': 1762770182, 'idTag': 'X16WG99J2QIEGCC0MCJ5-'}>}
2025-11-30 17:31:24.699 INFO (MainThread) [ocpp] 110A42BL0102: send [4,"4688","TypeConstraintViolation","Payload for Action is syntactically correct but at least one of the fields violates data type constraints (e.g. \u201csomestring\u201d: 12)",{"cause":"'X16WG99J2QIEGCC0MCJ5-' is too long","ocpp_message":"[2,"4688","StopTransaction",{"meterStop":250390,"timestamp":"2025-11-10T10:23:58Z","transactionId":1762770182,"idTag":"X16WG99J2QIEGCC0MCJ5-"}]"}]
`

[gabbuman]

Hey,

Changing config_flow.py will just prevent future configuration of the Central System ID to not be over 20 characters but will not fix the existing saved value that is already set for you: X16WG99J2QIEGCC0MCJ5-. This is still 21 characters long and violating the OCPP constraint.

Please change this to something that is less than 20 characters or just remove it so the system will use the default value: central