Skip to content

Error Handling

All API errors follow a consistent JSON format. Every error response contains a unique error ID, a machine-readable error code, a human-readable message, and a details array for field-specific validation errors.

Error Structure

{
  "error_id": "err_f47ac10b-58cc-4372-a567-0e02b2c3d479",
  "error_code": "ENTITY_NOT_FOUND",
  "message": "PlantInstance with key 'pi_xyz' not found.",
  "details": [
    {
      "field": "key",
      "reason": "No PlantInstance with key 'pi_xyz'.",
      "code": "ENTITY_NOT_FOUND"
    }
  ],
  "timestamp": "2026-03-17T10:30:00.000000+00:00",
  "path": "/api/v1/plant-instances/pi_xyz",
  "method": "GET"
}
Field Type Description
error_id String Unique UUID of the error event — use for support requests
error_code String Machine-readable code (full list below)
message String Short error description in English
details Array Field-specific error details (may be empty)
details[].field String Field name or path to the invalid value
details[].reason String Explanation of the specific problem
details[].code String Machine-readable detail code
timestamp String Time of the error (ISO 8601, UTC)
path String URL path of the failed request
method String HTTP method of the failed request

Use error_id for support

The error_id is logged on the server. Always include this ID when debugging or raising support requests — it allows the error to be traced precisely on the server side.

HTTP Status Codes

Code Meaning When
200 OK Success Read requests (GET)
201 Created Resource created POST with new resource
204 No Content Success without body DELETE
400 Bad Request Malformed request Syntax error in request body
401 Unauthorized Not authenticated Missing or invalid token
403 Forbidden No permission Authenticated but missing role
404 Not Found Resource not found Unknown ID or slug
409 Conflict Conflict Duplicate entry or invalid state transition
422 Unprocessable Entity Validation error Business rules violated (e.g. pre-harvest interval)
423 Locked Account locked Too many failed login attempts
429 Too Many Requests Rate limit exceeded Too many requests per minute
502 Bad Gateway External source unreachable GBIF/Perenual timeout
500 Internal Server Error Internal error Unexpected server error

Error Codes

General Errors

Error Code HTTP Description
ENTITY_NOT_FOUND 404 The requested resource does not exist
DUPLICATE_ENTRY 409 An entry with this value already exists
VALIDATION_ERROR 422 Pydantic validation error (types, required fields)
INTERNAL_ERROR 500 Unexpected internal error

Authentication and Authorization Errors

Error Code HTTP Description
UNAUTHORIZED 401 No valid token present
INVALID_TOKEN 401 Token expired or tampered
FORBIDDEN 403 Authenticated but without sufficient role
EMAIL_NOT_VERIFIED 403 Email address not yet confirmed
ACCOUNT_LOCKED 423 Account locked after too many failed attempts

Phase and State Errors

Error Code HTTP Description
PHASE_TRANSITION_INVALID 422 Invalid phase status transition (e.g. backward transition)
INVALID_STATUS_TRANSITION 422 Invalid status change of an object
INVALID_RUN_STATE 409 Operation not allowed in the current state

Plant Protection and Harvest Errors

Error Code HTTP Description
KARENZ_VIOLATION 422 Harvest not possible — pre-harvest interval (PHI) not yet elapsed
RESISTANCE_WARNING 422 Resistance risk — active ingredient applied too many times consecutively
HST_VIOLATION 422 Training measure (HST) not permitted in this growth phase

Substrate and Compatibility Errors

Error Code HTTP Description
SUBSTRATE_EXHAUSTED 422 Substrate batch has exceeded maximum reuse cycles
ROTATION_VIOLATION 422 Plant family was grown in this slot too recently
INCOMPATIBLE_COMPANION 422 Two plant species are incompatible as companion plants

External Services

Error Code HTTP Description
EXTERNAL_SOURCE_ERROR 502 External data service (GBIF, Perenual) not reachable
ADAPTER_NOT_FOUND 404 No adapter registered for the specified source
RATE_LIMIT_EXCEEDED 429 Rate limit of the server or an external service exceeded

Validation Errors (422)

FastAPI and Pydantic automatically produce structured validation errors for input mistakes. The details list contains one entry per invalid field:

POST /api/v1/auth/register
Content-Type: application/json

{
  "email": "not-a-valid-email",
  "password": "short",
  "display_name": ""
}

Response (422):

{
  "error_id": "err_b5e3c8a1-...",
  "error_code": "VALIDATION_ERROR",
  "message": "The input data is invalid.",
  "details": [
    {
      "field": "body.email",
      "reason": "value is not a valid email address",
      "code": "value_error"
    },
    {
      "field": "body.password",
      "reason": "String should have at least 10 characters",
      "code": "string_too_short"
    },
    {
      "field": "body.display_name",
      "reason": "String should have at least 1 character",
      "code": "string_too_short"
    }
  ],
  "timestamp": "2026-03-17T10:30:00.000000+00:00",
  "path": "/api/v1/auth/register",
  "method": "POST"
}

Pre-Harvest Interval Violation (KARENZ_VIOLATION)

The pre-harvest interval (PHI) gate prevents creating a harvest record while the waiting period of an applied pesticide has not yet elapsed.

POST /api/v1/t/my-garden/harvest/batches

Response (422) when PHI is active:

{
  "error_id": "err_c7d2e5f3-...",
  "error_code": "KARENZ_VIOLATION",
  "message": "Cannot harvest: safety interval for 'Pyrethrin' has 5 days remaining.",
  "details": [
    {
      "field": "active_ingredient",
      "reason": "Safety interval not elapsed: 5 days remaining.",
      "code": "KARENZ_VIOLATION"
    }
  ],
  "timestamp": "2026-03-17T10:30:00.000000+00:00",
  "path": "/api/v1/t/my-garden/harvest/batches",
  "method": "POST"
}

Pre-harvest intervals are legally relevant

The pre-harvest interval (Karenzzeit) between the last pesticide application and harvest is legally mandated by the PflSchG (German Plant Protection Act) and CanG (German Cannabis Act). Clients must never suppress or ignore this error.

Conflicts (409)

HTTP 409 is used when an operation cannot be performed due to the current state — for example, adding a plant to an already completed run:

{
  "error_id": "err_a1b2c3d4-...",
  "error_code": "INVALID_RUN_STATE",
  "message": "Operation 'add_plant' not allowed in status 'completed'.",
  "details": [],
  "timestamp": "2026-03-17T10:30:00.000000+00:00",
  "path": "/api/v1/t/my-garden/planting-runs/run_123/plants",
  "method": "POST"
}

Rate Limiting (429)

When the rate limit is exceeded, the API responds with HTTP 429. The Retry-After header indicates how many seconds to wait before retrying:

HTTP/1.1 429 Too Many Requests
Retry-After: 60

{
  "error": "Rate limit exceeded: 20 per 1 minute"
}

Internal Errors (500)

For unexpected internal errors, the API never exposes server-side details. The error_id is the only instrument for error correlation:

{
  "error_id": "err_9f8e7d6c-...",
  "error_code": "INTERNAL_ERROR",
  "message": "An internal error occurred. Please contact support with the reference ID.",
  "details": [],
  "timestamp": "2026-03-17T10:30:00.000000+00:00",
  "path": "/api/v1/t/my-garden/plant-instances/",
  "method": "GET"
}

Recommendations for API Clients

  • Evaluate the error code, not just the HTTP status code. Multiple semantically distinct errors can share the same status code. For example, KARENZ_VIOLATION, HST_VIOLATION, and ROTATION_VIOLATION are all HTTP 422.
  • Log the error_id. Always include the error_id in your own logs and in support requests.
  • Iterate the details array for field-specific error messages in form validation.
  • Respond to 401 with a token refresh. When the access token expires (15 min), the API returns 401 UNAUTHORIZED. The client should automatically attempt a refresh.
  • Do not retry 409 INVALID_RUN_STATE. This error indicates a business-level state conflict. The operation is only possible after a state change.

See Also