Errors

HTTP Error Response

HTTP APIs use a Google RPC Status-style JSON error body:

{
  "code": 16,
  "message": "Invalid username or password",
  "details": [
    {
      "@type": "type.googleapis.com/google.rpc.ErrorInfo",
      "reason": "UNAUTHENTICATED",
      "domain": "synctv.api",
      "metadata": {
        "errorCode": "1002",
        "errorKind": "unauthenticated",
        "requestId": "01HX..."
      }
    },
    {
      "@type": "type.googleapis.com/google.rpc.RequestInfo",
      "requestId": "01HX..."
    }
  ]
}

Field	Meaning
`code`	Numeric gRPC status code. The HTTP status still comes from the HTTP status line.
`message`	User-facing summary. 5xx details are sanitized.
`details[]`	Structured error details, usually including `google.rpc.ErrorInfo` with `reason`, `domain`, and `metadata`.
`details[].metadata.errorCode`	Application error code for programmatic handling.
`details[].metadata.requestId` / `google.rpc.RequestInfo.requestId`	Request identifier for log correlation.

429 may include a Retry-After header.

HTTP Status Codes

Status	Meaning	Client action
`400`	Invalid request structure, field, or format	Fix input; do not retry the same request
`401`	Not logged in, token expired, ticket expired, Provider credential expired	Refresh token, sign in, or rebind Provider
`403`	Authenticated but not allowed, email unverified, banned	Show permission reason
`404`	Resource, room, media, or Provider instance missing	Refresh local state
`409`	Already exists, concurrent update, state conflict	Read current state before retrying
`408`	Backend timeout	Retry with backoff
`429`	Rate limit or resource exhausted	Respect `Retry-After`
`502`	Upstream Provider or proxy error	Check Provider, upstream, and headers
`503`	Dependency or service unavailable	Retry later; operators check dependencies
`504`	Upstream timeout	Retry with backoff and inspect upstream

Application Error Codes

Range	Code	Meaning
Common	`0`	Unspecified
Auth	`1000`	Unauthenticated
Auth	`1001`	Token expired
Auth	`1002`	Invalid credentials
Resource	`2000`	Not found
Resource	`2001`	Already exists
Resource	`2002`	Resource exhausted or rate limited
Resource	`2003`	Conflict
Validation	`3000`	Invalid argument
Validation	`3001`	Invalid format
Validation	`3002`	Value too short
Validation	`3003`	Value too long
Validation	`3004`	Required field missing
Permission	`4000`	Permission denied
Permission	`4001`	Forbidden
Permission	`4002`	Banned
Server	`9000`	Internal error
Server	`9001`	Database error
Server	`9002`	Service unavailable
Server	`9003`	Timeout

Clients should not parse the message text for stable branching.

gRPC Errors

gRPC errors use the standard status code, message, and embedded google.rpc.Status binary details. HTTP-style x-synctv-error-code metadata is not sent as a separate trailer; clients should read google.rpc.ErrorInfo.metadata.errorCode and RetryInfo.

gRPC code	HTTP equivalent	Meaning
`InvalidArgument`	`400`	Invalid input
`Unauthenticated`	`401`	Missing or invalid auth
`PermissionDenied`	`403`	Authenticated but not allowed
`NotFound`	`404`	Resource missing
`AlreadyExists`	`409`	Resource already exists
`ResourceExhausted`	`429`	Rate limited or capacity exhausted
`Unavailable`	`503`	Service or dependency unavailable
`DeadlineExceeded`	`504`	Timeout
`Internal`	`500`	Internal server error

See gRPC Debugging.

Realtime Errors

WebSocket business errors use protobuf messages, not HTTP JSON:

Message	Scenario
`ServerMessage.error`	General business error, such as permission or invalid input
`ServerMessage.termination`	Server-initiated realtime stream termination with a dedicated `RealtimeTerminationCode` and display message
`ServerMessage.resourceObserveError`	Invalid observe id, too many observations, or resource load failure
WebSocket close	Auth failure, expired ticket, protocol error, connection limit, shutdown

Resource observation errors do not necessarily close the connection.

Provider Errors

Symptom	Typical status	Handling
Provider credential expired	`401`	Re-login or rebind Provider
Upstream resource missing	`404`	Refresh list and remove stale media
Upstream rejected request	`400` or `502`	Check headers, URL, format
Upstream rate limited or 5xx	`502`/`503`/`504`	Back off and inspect upstream
Credential encryption missing	Sanitized `500`	Configure credential encryption key

Client Rules

Classify by status: Use HTTP or gRPC status for login, permission, retry, and refresh decisions.
Use codes: Read application codes from google.rpc.ErrorInfo.metadata.errorCode. Do not parse English text.
Keep request IDs: Collect requestId, time, path, and status for support.
Protect secrets: Never log tokens, cookies, OAuth2 codes, Provider credentials, or passwords.