Zaptec unexpected status: 500 (Internal Server Error) and not charging (again)

[dirixmjm]

Describe the bug

I guess this is a duplicate of #21673 but there it is my understanding this issue was resolved.
I tried following the advice given there to go to the API documents and try manually, however I cannot find the "authorize" step.

I see the following error in the log, and the Zaptec 2 is unable to switch between 1 and 3 phase, neither charge current is switching correctly it seems.
Explorer: switch phases: unexpected status: 500 (Internal Server Error) POST https://api.zaptec.com/api/installation/e04dfb8e-77c1-48e2-b187-e335f5ed7cc9/update

Steps to reproduce

1. Start charge session
2. Review log

...

Configuration details

[main  ] INFO 2026/02/07 10:07:20 config file not found, database-only mode
[main  ] INFO 2026/02/07 10:07:20 using sqlite database: /root/.evcc/evcc.db?_pragma=busy_timeout(5000)
charger
---
db:3 {Type:template Title: Icon: Product:Zaptec Go 2} map[id:3d2e4118-dd8c-47b3-a2fb-30514353f5f8 password:***** template:zaptec user:*****]

meter
---
db:5 {Type:template Title: Icon: Product:Home Assistant} map[maxacpower:0 power:sensor.sessy_pd53_p1_power template:homeassistant uri:***** usage:grid]
db:7 {Type:template Title:SolarEdge Icon: Product:Home Assistant} map[maxacpower:0 power:sensor.solaredge_i1_ac_power template:homeassistant uri:***** usage:pv]
db:8 {Type:custom Title:Sessy Icon: Product:} map[yaml:## required attributes

power: # current power
  source: http
  uri: 10.0.10.117/api/v1/power/status
  method: GET
  headers:
    - content-type: application/json
  auth:
    type: basic
    user: *
    password: *
  insecure: false
  jq: .sessy.power
  cache: 60s
  timeout: 10s

energy: # meter reading in kWh
  source: http
  uri: 10.0.10.117/api/v1/energy/status
  method: GET
  headers:
    - content-type: application/json
  auth:
    type: basic
    user: *
    password: *
  insecure: false
  jq: .sessy_energy.import_wh
  cache: 60s
  timeout: 10s

soc: # meter reading in kWh
  source: http
  uri: 10.0.10.117/api/v1/power/status
  method: GET
  headers:
    - content-type: application/json
  auth:
    type: basic
    user: *
    password: *
  insecure: false
  jq: .sessy.state_of_charge
  cache: 60s
  timeout: 10s

capacity: 5]

vehicle
---
db:6 {Type:template Title: Icon: Product:Ford (FordConnect Query)} map[cache:15m capacity:77 clientid:8df5ddba-3057-4924-a5fc-ceed0849f0ba clientsecret:***** icon:car redirecturi:https://evcc.dirix.nu:7070/providerauth/callback template:ford-connect-query title:Explorer vin:*****]

loadpoint
---
db:4 {Type: Title: Icon: Product:} map[charger:db:3 circuit: defaultMode:minpv limitSoc:0 maxCurrent:16 meter: mode:minpv phasesConfigured:3 planEnergy:0 planStrategy:map[continuous:false precondition:0] planTime:0001-01-01T00:00:00Z smartCostLimit:0.1 soc:map[estimate:true poll:map[interval:3.6e+12 mode:charging]] thresholds:map[disable:map[delay:1.8e+11 threshold:0] enable:map[delay:6e+10 threshold:0]] title:Zaptec vehicle:]

Log details

[site ] DEBUG 2026/02/07 10:02:32 ----
[lp-1 ] DEBUG 2026/02/07 10:02:33 charge power: 10323W
[lp-1 ] DEBUG 2026/02/07 10:02:33 charge currents: [15.1 15.2 15.4]A
[site ] DEBUG 2026/02/07 10:02:33 grid power: 9510W
[site ] DEBUG 2026/02/07 10:02:33 battery 1 power: 0W
[site ] DEBUG 2026/02/07 10:02:33 pv 1 power: 1716W
[site ] DEBUG 2026/02/07 10:02:33 !! solar production: accumulate add db:7 0.000W power (was: Accumulated: 0.564kWh updated: 2026-02-07 10:02:03 +0100 CET)
[site ] DEBUG 2026/02/07 10:02:33 !! solar production: accumulate moved db:7 from 0.564 to 0.579
[site ] DEBUG 2026/02/07 10:02:33 battery 1 soc: 0%
[site ] DEBUG 2026/02/07 10:02:33 site power: 9510W
[lp-1 ] DEBUG 2026/02/07 10:02:33 detected active phases: 3p
[lp-1 ] DEBUG 2026/02/07 10:02:33 session energy: 1.852kWh
[lp-1 ] DEBUG 2026/02/07 10:02:33 charger status: C
[lp-1 ] DEBUG 2026/02/07 10:02:33 vehicle soc: 52%
[lp-1 ] DEBUG 2026/02/07 10:02:33 vehicle range: 202km
[lp-1 ] DEBUG 2026/02/07 10:02:33 soc estimated: 54.04% (vehicle: 52.00%)
[lp-1 ] DEBUG 2026/02/07 10:02:33 vehicle soc (estimator): 54%
[lp-1 ] DEBUG 2026/02/07 10:02:33 plan: charge 1h42m14s between 2026-02-07 12:45:00 +0100 CET until 2026-02-07 17:00:00 +0100 CET (power: 13800W, avg cost: 0.088)
[lp-1 ] ERROR 2026/02/07 10:02:33 switch phases: unexpected status: 500 (Internal Server Error) POST https://api.zaptec.com/api/installation/e04dfb8e-77c1-48e2-b187-e335f5ed7cc9/update

What type of operating system or environment does evcc run on?

Linux

External automation

• I have made sure that no external automation like HomeAssistant or Node-RED is active or accessing any of the mentioned devices when this issue occurs.

Nightly build

• I have verified that the issue is reproducible with the latest nightly build

Version

evcc version 0.300.8 (a789661)

[andig]

Device issues need TRACE log included, please add here

[dirixmjm]

This is sufficient?

[zaptec] TRACE 2026/02/07 10:35:57 GET https://api.zaptec.com/api/chargers/3d2e4118-dd8c-47b3-a2fb-30514353f5f8/state
[zaptec] TRACE 2026/02/07 10:35:57 [{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":-3,"Timestamp":"2026-02-07T08:50:58.083","ValueAsString":"1"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":-2,"Timestamp":"2026-02-07T08:50:56.71","ValueAsString":"1"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":-1,"Timestamp":"2026-02-07T09:35:07.83"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":1,"Timestamp":"2025-09-21T09:11:17.29","ValueAsString":"0"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":100,"Timestamp":"2025-09-21T09:28:53.663","ValueAsString":"{\"CommunicationModes\":[\"LTE\",\"WiFi\"],\"DeviceType\":\"Go\",\"MeterCalibrated\":true,\"OcppVersions\":[\"V1_6\"],\"PhaseBalancing\":[\"ThreeToOneFixed\"],\"ProductVariant\":\"Go2\",\"SchemaVersion\":\"2.2\"}"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":120,"Timestamp":"2025-09-21T09:35:05.187","ValueAsString":"1"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":145,"Timestamp":"2025-09-21T09:28:53.637","ValueAsString":"300"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":147,"Timestamp":"2026-02-07T09:14:07.667","ValueAsString":"180"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":150,"Timestamp":"2025-09-21T09:28:55.797","ValueAsString":"Wifi"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":151,"Timestamp":"2025-12-02T06:28:37.77","ValueAsString":"1"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":153,"Timestamp":"2025-09-26T13:15:06.463","ValueAsString":"0.300"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":157,"Timestamp":"2025-11-21T14:42:11.987","ValueAsString":"zap-p-iothub-03.azure-devices.net"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":158,"Timestamp":"2025-11-21T14:42:11.99","ValueAsString":"0ne00FE5F86"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":160,"Timestamp":"2025-11-21T14:42:11.99","ValueAsString":"PROD DEFAULT"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":201,"Timestamp":"2026-02-07T09:31:58.963","ValueAsString":"23.227"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":202,"Timestamp":"2026-02-07T09:31:59.027","ValueAsString":"20.278"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":204,"Timestamp":"2026-02-07T09:31:59.027","ValueAsString":"20.931"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":205,"Timestamp":"2026-02-07T09:31:59.027","ValueAsString":"20.606"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":206,"Timestamp":"2026-02-07T09:31:59.03","ValueAsString":"17.756"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":207,"Timestamp":"2026-02-07T09:31:59.03","ValueAsString":"20.979"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":220,"Timestamp":"2026-02-06T06:51:51.02","ValueAsString":"20.271"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":221,"Timestamp":"2026-02-06T06:51:51.023","ValueAsString":"12.624"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":270,"Timestamp":"2026-02-07T09:31:58.963","ValueAsString":"46.677"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":280,"Timestamp":"2025-09-21T09:28:53.23","ValueAsString":"2"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":281,"Timestamp":"2026-02-07T09:31:58.963","ValueAsString":"1535"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":501,"Timestamp":"2026-02-07T09:31:59.033","ValueAsString":"230.755"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":502,"Timestamp":"2026-02-07T09:31:59.033","ValueAsString":"223.367"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":503,"Timestamp":"2026-02-07T09:31:59.033","ValueAsString":"225.301"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":507,"Timestamp":"2026-02-07T09:31:59.03","ValueAsString":"15.251"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":508,"Timestamp":"2026-02-07T09:31:59.03","ValueAsString":"15.416"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":509,"Timestamp":"2026-02-07T09:31:59.033","ValueAsString":"15.620"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":510,"Timestamp":"2026-02-07T08:50:17.563","ValueAsString":"16.000"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":511,"Timestamp":"2026-02-07T08:50:17.567","ValueAsString":"6.000"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":513,"Timestamp":"2026-02-07T09:31:58.967","ValueAsString":"10436.226"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":516,"Timestamp":"2026-02-07T09:31:59.037","ValueAsString":"11.825"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":517,"Timestamp":"2026-02-07T09:31:59.037","ValueAsString":"0.327"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":519,"Timestamp":"2026-02-07T09:14:19.547","ValueAsString":"4"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":520,"Timestamp":"2025-09-21T09:08:43.89","ValueAsString":"3"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":522,"Timestamp":"2025-09-21T09:08:43.89","ValueAsString":"1"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":523,"Timestamp":"2025-10-07T02:14:40.09","ValueAsString":"1.000"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":544,"Timestamp":"2025-09-21T09:28:53.637","ValueAsString":"2"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":545,"Timestamp":"2025-09-21T09:08:43.443","ValueAsString":"0"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":546,"Timestamp":"2025-09-21T09:09:31.31","ValueAsString":"20.000"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":547,"Timestamp":"2025-09-21T09:09:32.35","ValueAsString":"20.000"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":548,"Timestamp":"2025-09-21T09:08:43.517","ValueAsString":"4"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":553,"Timestamp":"2026-02-07T09:33:07.9","ValueAsString":"5.966"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":554,"Timestamp":"2026-02-07T09:00:02.503","ValueAsString":"OCMF|{\"FV\":\"1.0\",\"GI\":\"Zaptec Go 2\",\"GS\":\"GPN006973\",\"GV\":\"3.2.1.0\",\"MF\":\"v2.6.7\",\"PG\":\"F1\",\"RD\":[{\"TM\":\"2026-02-07T09:00:00,177+00:00 S\",\"RV\":1479.736,\"RI\":\"1-0:1.8.0\",\"RU\":\"kWh\",\"RT\":\"AC\",\"ST\":\"G\"}]}|{\"SA\":\"ECDSA-secp384r1-SHA256\",\"SE\":\"base64\",\"SD\":\"MGUCMBMV0I3vzb2A+LJ23vpBNaFa5GqmY6IvHxYpNlGpgo8u6kGxrsvWw8x4vt/qTHx4ZgIxALjM5GxG7Njp4ph5AryEdhTlHzsGdNLGgXLXSVGM1Zxd6QiEopJkfSnXXu6nxe1Vog==\"}"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":702,"Timestamp":"2026-02-07T09:03:53.463","ValueAsString":"6"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":703,"Timestamp":"2026-02-07T09:31:59.04","ValueAsString":"2928"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":705,"Timestamp":"2026-02-07T06:15:09.68","ValueAsString":"736"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":708,"Timestamp":"2026-02-07T09:14:20.127","ValueAsString":"15.984"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":710,"Timestamp":"2026-02-07T09:14:06.81","ValueAsString":"3"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":711,"Timestamp":"2025-09-21T09:11:17.317","ValueAsString":"1"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":712,"Timestamp":"2025-10-04T15:03:19.5","ValueAsString":"0"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":714,"Timestamp":"2025-10-07T17:31:02.597","ValueAsString":"32"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":715,"Timestamp":"2025-09-21T09:08:43.4","ValueAsString":"4"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":718,"Timestamp":"2026-02-05T15:31:58.843","ValueAsString":"0"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":721,"Timestamp":"2026-02-07T08:51:25.763","ValueAsString":"804c233f-94aa-44b0-945e-5491bc1aa4c2"},{"ChargerId":"3d2e4118-dd8c-47b3-a2fb-30514353f5f8","StateId":722,"Timestamp":"2026-02-07T08
[zaptec] TRACE 2026/02/07 10:35:57 POST https://api.zaptec.com/api/installation/e04dfb8e-77c1-48e2-b187-e335f5ed7cc9/update
[zaptec] TRACE 2026/02/07 10:35:57 {"availableCurrentPhase1":20,"availableCurrentPhase2":20,"availableCurrentPhase3":20} -- {"Code":527,"Details":"Cannot update installation when using APM"} 

[andig]

No.

[dirixmjm]

Ok, adding a somewhat longer trace.

Is it possible that EVCC tries to set a maximum charge current (20A maximum setting for the Zaptec) which is reject because of the either the car (Explorer EV, max 16A) does not allow it, or the Zaptec internal control loop (APM) rejects it due to the maximum current limit of the house as I have a Zaptec P1 meter.

evcc-20260207-104910-trace.log

If the trace is not enough, could you please give me a hint what to do next?

[andig]

{"Code":527,"Details":"Cannot update installation when using APM"}

Maybe @ttomasini knows. Also seems that the Zaptec implementation is lacking error handling when the charger returns HTTP 200 with error response body.

[andig]

With 201b93f, and status code >= 300 should return an error, even when not decoding the JSON response. Maybe this helps here to catch the error earlier.