Error codes¶

Sluice puts one of these codes in the code field of an error response. MCP tool errors use the same codes. REST API shows the response body.

Code	HTTP status	Meaning
`ERR_SYNTAX`	400	SQL parse error
`ERR_MULTIPLE_STATEMENTS`	400	Only a single statement is allowed per request
`ERR_UNSUPPORTED_SYNTAX`	400	SQL feature not supported
`ERR_REWRITE_FAILED`	400	Policy rewrite failed
`ERR_MASK_UNSUPPORTED_CONTEXT`	400	A post-query masked column is used outside a bare select item
`ERR_UNAUTHORIZED`	401	Authentication required
`ACL_DENIED`	403	Access denied by policy
`ACL_REJECTED`	403	Query shape rejected by policy
`ERR_DATASOURCE_UNAVAILABLE`	503	Data source unavailable
`ERR_POLICY_UNAVAILABLE`	503	Policy engine unavailable; request refused (fail-closed)
`ERR_CONFIG_INVALID`	400	Server configuration invalid
`ERR_POLICY_INVALID`	400	Policy document invalid
`ERR_TIMEOUT`	504	Request timed out
`ERR_CANCELED`	499	Request canceled
`ERR_QUERY_FAILED`	400	The database rejected the query
`ERR_RATE_LIMITED`	429	Too many requests
`ERR_BUDGET_EXCEEDED`	429	Query budget exceeded
`ERR_PAYLOAD_TOO_LARGE`	413	Payload too large
`ERR_RESULT_TRUNCATED`	200	Result truncated
`ERR_AUDIT_UNAVAILABLE`	503	Audit log unavailable; request refused (fail-closed)
`ERR_APPROVAL_PENDING`	202	Query requires human approval; awaiting decision
`ERR_APPROVAL_REJECTED`	403	Query rejected by an approver
`ERR_APPROVAL_EXPIRED`	410	Approval request expired before a decision was made
`ERR_INTERNAL`	500	Internal error

ERR_RESULT_TRUNCATED is a warning in a successful response, not an error.
A policy can replace ACL_DENIED or ACL_REJECTED with its own code. The HTTP status stays 403.
Only POST /admin/reload returns ERR_CONFIG_INVALID and ERR_POLICY_INVALID.