Errors

All errors share the same JSON envelope, whatever the endpoint.

{
  "message": "Promo code already exists",
  "errorCode": "400:PROMO_CODE_ALREADY_EXISTS",
  "path": "/coupons",
  "date": "2026-01-15T09:30:00.000Z"
}

Field	Type	Description
message	string	Human-readable message, translated according to x-lang. Display it, don't test it.
errorCode	string	<HTTP status>:<CODE>. Stable: this is the field your code should test.
path	string	The URL called, including the query string.
date	string	ISO 8601 timestamp.
details	object	Optional. Values that help with diagnosis (e.g. remaining credits).
validationErrors	array	Only present for 400:VALIDATION_ERROR: [{field, message}].

Validation errors

{
  "message": "email must be an email",
  "errorCode": "400:VALIDATION_ERROR",
  "path": "/clients",
  "date": "2026-01-15T09:30:00.000Z",
  "validationErrors": [
    {"field": "email", "message": "email must be an email"},
    {"field": "lastName", "message": "lastName must be longer than or equal to 2 characters"}
  ]
}

message repeats the first error. For nested objects, field holds the name of the leaf field (backgroundColor), not the full path.

Handle errors properly

const res = await fetch(url, options);
if (!res.ok) {
  const err = await res.json();
  const [, code] = err.errorCode.split(':');
  switch (code) {
    case 'UNAUTHORIZED':
      // token expired: log in again
      break;
    case 'VALIDATION_ERROR':
      // fix the fields listed in err.validationErrors
      break;
    case 'PASS_BUILDER_ERROR':
      // temporary pass generation error: retry later
      break;
    default:
      throw new Error(`${err.errorCode}: ${err.message}`);
  }
}

• 4xx: the request is at fault. Don't resend it as is.
• 5xx: an error on eldo wallet's side. Retry with an increasing delay (1 s, 2 s, 4 s…).
• Each page of the API reference lists the errors specific to that endpoint, with a sample response.

All codes

HTTP	messageCode	Message	What to do
204	NOTHING_TO_UPDATE	Nothing to update!
400	ACTIVE_WELCOME_COUPON_ALREADY_EXISTS	Active welcome coupon already exists
400	ALL_CLIENTS_ALREADY_HAVE_COUPON	All provided clients already have this coupon
400	ARRIVAL_TIME_MUST_BE_AFTER_DEPARTURE_TIME_CONSIDERING_DATES	Arrival time must be after departure time considering dates
400	BATCH_LIMIT_EXCEEDED	Batch limit exceeded (max 100)
400	CENTER_ROW_IS_REQUIRED	Center row is required
400	CHECKOUT_MUST_BE_AFTER_CHECKIN	Checkout must be after checkin
400	CLIENT_DOES_NOT_BELONG_TO_THIS_WALLET	Client does not belong to this wallet
400	CLIENTS_EXIST_FOR_THIS_CARD_TYPE	Clients exist for this card type
400	COMMUNICATION_DELETED	Communication is deleted and cannot be updated
400	DEFAULT_CLIENT_TYPE_REQUIRED	At least one client type must remain default
400	ERROR_CUSTOMER_TYPE_ASSIGNMENT	Error customer type assignment
400	FILE_REQUIRED	File is required
400	HOTEL_HAS_PASSES	Hotel has passes!
400	INSTANT_COMMUNICATION_ALREADY_EXISTS	Instant communication already exists
400	INSUFFICIENT_CREDIT	Insufficient {creditType} credit: {required} required, {remaining} remaining
400	INVALID_DATE_RANGE	endDate must be on or after startDate.
400	INVALID_DEPARTURE_OR_ARRIVAL_DATETIME_FORMAT	Invalid departure or arrival datetime format
400	INVALID_DEVICE_TYPE	Invalid device type: {deviceType}
400	INVALID_JSON	Invalid JSON syntax in request body
400	INVALID_MULTIPART	Invalid multipart request: missing or malformed boundary in Content-Type header. Use multipart/form-data with a valid boundary for file uploads, or application/json for JSON-only updates.
400	INVALID_PASS_KIND	Invalid pass kind
400	INVALID_PASS_TYPE	Invalid pass type: {passType}
400	INVALID_STATUS	Invalid status provided
400	INVALID_WALLET_OBJECT_TYPE	Invalid wallet object type: {objectType}
400	LEFT_ROW_IS_REQUIRED	Left row is required
400	MAX_WALLET_LOCATIONS_REACHED	Max wallet locations reached
400	MISSING_ANDROID_OBJECT_ID	Missing Android object ID
400	MISSING_BARCODE	Missing barcode
400	MISSING_RECIPIENT_DETAILS_FOR_NON_CLIENT	Missing recipient details (firstName, lastName, email) for non-client recipient
400	MISSING_REQUIRED_FIELDS	Missing required fields: {fields}
400	NO_CLIENTS_FOUND	No clients found
400	NO_CUSTOMERS_FOUND	No customers found
400	NO_PASS_DATA_PROVIDED	No pass data provided
400	NO_RECIPIENTS_PROVIDED	No recipients provided
400	OPERATION_TYPE_NOT_ALLOWED	operationType is only allowed when transactionType is OPERATION
400	OPERATION_TYPE_REQUIRED	operationType is required when transactionType is OPERATION
400	PACK_ALREADY_EXISTS	Pack name already exists
400	PACK_INSUFFICIENT_CREDITS	Cannot assign pack: this wallet has {clientsCount} clients, but the pack's {creditTypes} credit(s) allow fewer than that
400	PASS_ALREADY_CANCELED	Cannot update a canceled pass
400	PASS_ALREADY_EXPIRED	Pass already expired
400	PASS_ALREADY_GENERATED	Pass already generated
400	PASS_ALREADY_REDEEMED	Pass is already redeemed
400	PASS_NOT_REDEEMED	Pass is not redeemed
400	PROMO_CODE_ALREADY_EXISTS	Promo code already exists
400	RIGHT_ROW_IS_REQUIRED	Right row is required
400	SCHEDUle_DATE_PASSED	Schedule date has already passed
400	SMS_CONFIG_REQUIRED	SMS configuration is required
400	SMS_CREDENTIALS_NOT_CONFIGURED	SMS credentials are not configured for this wallet
400	SMS_TITLE_IS_REQUIRED	SMS title is required
400	SYNC_EXECUTION_NOT_ALLOWED	Synchronous execution is not allowed for bulk operations with 1000 or more items. Please set forceSync to false or reduce the number of items below 1000.
400	SYNC_EXECUTION_NOT_ALLOWED_FOR_BULK_UPDATE_CLIENTS	Synchronous execution is not allowed for bulk update clients with 1000 or more items. Please set forceSync to false or reduce the number of items below 1000.
400	SYSTEM_DOES_NOT_SUPPORT_MORE_THAN_100000_CUSTOMERS	System does not support more than 100,000 customers
400	UNEXPECTED_FIELD	Unexpected field: {field}
400	UNLIMITED_COMMUNICATION_ALREADY_EXISTS	Unlimited communication already exists
400	UNSUPPORTED_EVENT_TYPE:	Unsupported event type: {eventType}
400	USE_OTHER_SERVICE_COMMUNICATION_DELETE	Use delete service to delete communication
400	USER_ALREADY_EXISTS	User already exists
400	VALIDATION_ERROR	Validation error!
400	WALLET_IDENTIFIER_REQUIRED	Wallet identifier is required for pass template creation
400	WALLET_NOT_CONFIGURED	Wallet is not configured with pass-builder. Please complete wallet migration first.
401	PASSBUILDER_TOKEN_MISSING	PassBuilder token is missing
401	UNAUTHORIZED	Unauthorized!
403	FORBIDDEN	Forbidden!
404	CERTIFICATE_NOT_FOUND	Certificate not found!
404	CLASS_NOT_FOUND	Requested Google Wallet class not found.
404	COUPON_TEMPLATE_NOT_FOUND	Coupon template not found
404	CREATE_WALLET_CLASS_FAILED	Failed to create Google Wallet class.
404	INITIALIZE_WALLET_OBJECT_CLIENT_FAILED	Failed to initialize Google Wallet client.
404	MISSING_ANDROID_CLASS_ID	Missing Android class ID
404	MISSING_FIELD	Missing field: {field}
404	MODEL_NOT_FOUND	Model not found!
404	OBJECT_CREATION_FAILED	Failed to create Google Wallet object.
404	OBJECT_NOT_FOUND	Object not found
404	OBJECT_UPDATE_FAILED	Failed to update Google Wallet object.
404	PACK_NOT_ASSIGNED	No credit pack is assigned to this wallet.
404	PASS_BUILDER_PASS_ID_NOT_FOUND	Pass builder pass ID not found
404	PASS_NOT_FOUND	Pass not found
404	PASSBUILDER_UPDATE_FAILED	Failed to update wallet with PassBuilder info
404	PATH_NOT_FOUND	Path not found!
404	STORECARD_NOT_FOUND	Storecard pass not found
404	TEMPLATE_NOT_FOUND	Template not found : {templateName}
404	TOKEN_MISMATCH_OR_DEVICE_NOT_FOUND	Token mismatch or device not found
404	UNSUPPORTED_WALLET_TYPE	Unsupported wallet type
404	UPDATE_OPERATION_NOT_SUPPORTED	Update operation not supported
404	UPDATE_WALLET_CLASS_FAILED	Failed to update Google Wallet class.
404	WALLET_NOT_FOUND	Wallet not found
404	WALLET_UPDATE_FAILED	Failed to update wallet
409	BARCODE_ALREADY_EXISTS	Barcode already exists
409	CLIENT_ALREADY_EXISTS	Client already exists
409	EMAIL_ALREADY_EXISTS	Email already exists
409	INSUFFICIENT_CREDIT_PARTIAL	Some channels do not have enough credit to notify every client. Confirm to send only on the channels that do.
409	OVERLAPPING_COMMUNICATIONS	Overlapping communications exist for the selected dates
409	OVERLAPPING_DATES	Hotel is already reserved for the selected dates
409	PACK_HAS_ASSIGNED_MANAGERS	Cannot delete pack: managers are still assigned to it
409	PASSBUILDER_IDENTITY_INCOMPLETE	PassBuilder identity is incomplete or contradictory. Repair the wallet before continuing.
409	PASSBUILDER_IDENTITY_PROVISIONING	PassBuilder identity provisioning is already in progress. Retry shortly.
409	PUSH_NOTIFICATION_SCHEDULE_CONFLICT	A notification is already scheduled at this date and time. Please choose another time at least {seconds} seconds apart.
409	STORE_CARD_ALREADY_EXISTS	This wallet already has a loyalty card
409	TEMPLATE_ALREADY_EXISTS	Template already exists
415	UNSUPPORTED_MEDIA_TYPE	Unsupported Content-Type. Use application/json or multipart/form-data.
500	BATCH_OPERATION_FAILED	Batch operation failed: {error}
500	GOOGLE_AUTH_INIT_FAILED	Failed to initialize Google Auth client.
500	UNKNOWN_ERROR	Unknown error!
500	WALLET_CLIENT_INIT_FAILED	Failed to initialize Google Wallet client.
500	WALLET_UPDATE_ERROR	An error occurred while updating the wallet
502	SMS_CREDIT_LOOKUP_FAILED	Failed to retrieve SMS credit information
502	SMS_LOGIN_FAILED	Failed to authenticate with the SMS provider
502	SMS_SEND_FAILED	Failed to send SMS through the provider
503	PASS_BUILDER_ERROR	External service error