generated: '2026-08-19'
method: probed
source: >-
  Error responses actually elicited from Yale-operated hosts on 2026-08-19. Every body quoted below
  was returned to a real request; none is illustrative.
description: >-
  Observed error semantics across Yale University's machine-readable surfaces. Yale has no single
  error contract — each surface carries the error idiom of the stack it is built on, and one of
  them is currently failing.
errors:
- surface: LUX Collections Discovery API
  base_url: https://lux.collections.yale.edu
  x-operator: institution
  media_type: application/json
  shape: '{"statusCode": <int>, "errorMessage": <string>}'
  observed:
  - request: GET /api/search-estimate/item?q=gold
    status: 400
    body: '{"statusCode":400,"errorMessage":"Document is not JSON"}'
    interpretation: >-
      The q parameter must be LUX JSON Grammar or String Grammar, not a bare keyword. The message
      is machine-stable and names the actual fault. Re-issued as
      q={"text":"gold"} the same endpoint returned 200 with totalItems 53387.
  assessment: >-
    Structured, JSON, specific. Good. Not documented in any published error table, and the status
    code is duplicated inside the body rather than described in the contract.
- surface: Yale Dataverse Repository API
  base_url: https://dataverse.yale.edu
  x-operator: institution
  media_type: application/json
  shape: '{"status": "ERROR", "message": <string>}'
  observed:
  - request: 'GET /api/info/settings/:DatasetPublishPopupCustomText'
    status: 404
    body: '{"status":"ERROR","message":"Setting :DatasetPublishPopupCustomText not found"}'
  - request: 'GET /api/datasets/export?exporter=schema.org&persistentId=doi:10.60600/QTNBFE'
    status: 404
    body: '{"status":"ERROR","message":"A dataset with the persistentId doi:10.60600/QTNBFE could not be found."}'
  assessment: >-
    Consistent envelope, human-readable message, correct status codes. No machine-readable error
    code field, so callers must string-match. This is the Dataverse software's contract, inherited
    rather than authored by Yale.
- surface: Yale Dataverse OAI-PMH
  base_url: https://dataverse.yale.edu
  x-operator: institution
  media_type: text/html
  shape: Payara application-server error report page
  observed:
  - request: GET /oai?verb=Identify
    status: 503
    body: 'Payara Server 7.2026.2 - Error report'
  - request: GET /oai?verb=ListMetadataFormats
    status: 503
    body: 'Payara Server 7.2026.2 - Error report'
  assessment: >-
    A LIVE DEFECT, recorded as such. The OAI-PMH harvesting endpoint is present and routed but the
    application server is returning 503 with a raw stack-page instead of an OAI-PMH error element.
    Harvesters cannot distinguish this from the repository being down. This is the single
    highest-value fix on Yale's institution-operated estate.
- surface: Yale Portal APIs gateway
  base_url: https://gw.its.yale.edu
  x-operator: institution
  media_type: text/plain
  shape: bare string
  observed:
  - request: GET /soa-gateway/courses/webservice/v3/index
    status: 400
    body: 'Invalid API Key'
  assessment: >-
    The gateway answers, which proves the surface is live rather than retired — but an authentication
    failure is being reported as 400 with a plain-text body rather than 401 with a structured
    payload and a WWW-Authenticate header. Semantically wrong status code.
- surface: Yale University Library Digital Collections
  base_url: https://collections.library.yale.edu
  x-operator: institution
  media_type: text/html
  observed:
  - request: GET /manifests/collections/2055095
    status: 404
    body: "We're sorry, but the item you've requested does not appear to exist"
    interpretation: Honest 404 with a real body — not a soft-404.
  - request: GET /catalog.json?q=test
    status: 202
    body: '(empty, zero bytes)'
    interpretation: >-
      An empty 202 to a JSON request is an edge bot challenge, not an application response. Retried
      with a browser User-Agent and an explicit Accept header; unchanged. Recorded as blocked at
      the edge — a fact about our access, not a fact about Yale's engineering.
  - request: GET /oai?verb=Identify
    status: 404
    interpretation: No OAI-PMH endpoint on the digital collections host.
- surface: Yale main web estate
  base_url: https://www.yale.edu
  x-operator: institution
  observed:
  - request: GET /llms.txt
    status: 404
  - request: GET /.well-known/security.txt
    status: 404
  assessment: >-
    Neither an agent-facing content declaration nor an RFC 9116 security contact is published at the
    apex. robots.txt is present (200, 2491 bytes).