> ## Documentation Index > Fetch the complete documentation index at: https://docs.arcuserp.com/llms.txt > Use this file to discover all available pages before exploring further. # Update a contact > Updates one or more fields on an existing account contact. All body fields are optional; supply only the fields to change. Setting `is_primary: true` automatically demotes the current primary contact for the account. Requires `accounts:write` scope. Field aliases: `role` accepted as alias for `title`; `phone_main` accepted as alias for `phone`. ## OpenAPI ````yaml /openapi.yaml patch /accounts/{id}/contacts/{cnt_id} openapi: 3.1.0 info: title: Arcus ERP Public API version: 1.0.0 description: > Arcus ERP public REST API. Designed for external integrations and data migration. **Authentication.** Bearer token (API key) via the `Authorization` header. Format: `Authorization: Bearer ark_live_ent__` (or `ark_test_*` for sandbox). API keys are issued per-entity in **Settings > Developers > API Keys**. **Entity scoping.** The entity is encoded in the API key prefix; routes are flat (e.g. `/v1/accounts`, `/v1/orders`, `/v1/products`). A small set of platform endpoints (migration, reconciliation, events, webhook endpoints, API keys) use the `/v1/entities/{entity_id}/...` form -- those are noted in their tags. **Key capabilities.** - Related-resource hydration via `?expand[]=` (see `x-arcus-expand` on each resource). - Cursor-based pagination (`starting_after` / `ending_before` / `limit`). - Idempotency via the `Idempotency-Key` header. - Webhook events for asynchronous notification. - Conditional requests / ETag for cache validation. servers: - url: https://api.arcuserp.com/v1 description: Arcus ERP API (accepts both live `ark_live_*` and test `ark_test_*` keys) - url: https://dev-api.arcuserp.com/v1 description: >- Dev sandbox API (test-only data, accepts `ark_test_*` keys against dev RDS) security: [] paths: /accounts/{id}/contacts/{cnt_id}: parameters: - name: id in: path required: true schema: type: string format: uuid - name: cnt_id in: path required: true schema: type: string format: uuid patch: tags: - Accounts summary: Update a contact description: > Updates one or more fields on an existing account contact. All body fields are optional; supply only the fields to change. Setting `is_primary: true` automatically demotes the current primary contact for the account. Requires `accounts:write` scope. Field aliases: `role` accepted as alias for `title`; `phone_main` accepted as alias for `phone`. operationId: updateAccountContact requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/AccountContactCreate' responses: '200': description: Updated contact content: application/json: schema: type: object properties: data: $ref: '#/components/schemas/AccountContact' '401': $ref: '#/components/responses/Error' '403': $ref: '#/components/responses/Error' '404': $ref: '#/components/responses/Error' security: - ApiKeyAuth: - accounts:write components: schemas: AccountContactCreate: type: object description: > Contact payload accepted by both standalone contact endpoints and the atomic-create path in POST /v1/accounts. **Field aliases (all paths, all operations):** - `role` accepted as alias for `title` (public API convenience) - `phone_main` accepted as alias for `phone` FIX 2026-05-15 (NEW-GAP-API-V1-ADDRESS-AND-CONTACT-FIELD-MAPPING-INCONSISTENT): Aliases now work in standalone POST/PATCH endpoints (previously only worked in atomic-create). properties: first_name: type: string nullable: true last_name: type: string nullable: true email: type: string nullable: true phone: type: string nullable: true description: Phone number. Also accepted as `phone_main` (alias). phone_main: type: string nullable: true description: Alias for phone. title: type: string nullable: true description: Job title or role. Also accepted as `role` (alias). role: type: string nullable: true description: Alias for title. website: type: string nullable: true is_primary: type: boolean AccountContact: type: object description: A person contact associated with an account. properties: id: type: string format: uuid account_id: type: string format: uuid first_name: type: string nullable: true last_name: type: string nullable: true email: type: string nullable: true phone: type: string nullable: true title: type: string nullable: true website: type: string nullable: true is_primary: type: boolean external_source: type: string nullable: true description: | Provenance label for rows imported from external systems (e.g. `versa_cloud`, `bubble`, `shopify`). Used with `external_id` for migration back-read. external_id: type: string nullable: true description: The source system's row identifier for this contact. created_at: type: string format: date-time readOnly: true ErrorEnvelope: type: object description: | Canonical error response envelope. All API errors use this shape. required: - error - code properties: error: type: string description: Machine-readable error key example: not_found code: type: string description: Machine-readable error code (often same as error) example: not_found type: type: string enum: - validation_error - permission_error - not_found - conflict - rate_limit - internal - expand_error - not_implemented example: not_found hint: type: string description: Human-readable one-sentence explanation (English) example: >- The requested order does not exist or does not belong to this entity. param: type: string description: The parameter that caused the error, if applicable example: expand[0] required: type: string description: The scope required (only on insufficient_scope errors) example: accounts:read request_id: type: string description: >- Unique request ID for support tracing (maps to CloudWatch log stream) example: req_abc123 responses: Error: description: Error response (400/401/403/404/409/422/429/500) content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' securitySchemes: ApiKeyAuth: type: http scheme: bearer description: | API key issued per entity via Settings > Developers > API Keys. Each key carries scopes (e.g. orders:read, products:write). Bearer token format: Authorization: Bearer ark_live_ent__ Test keys use ark_test_ent__. Both are issued per entity via Settings > Developers > API Keys. ````