Sierra: XCirc error 500 "This record is not available"

{
  "detail": "Unexpected response from: POST /iii/sierra-api/v6/patrons/1082119/holds/requests",
  "requestUrl": "https://sierra-app.wdm.iowa.gov/iii/sierra-api/v6/patrons/1082119/holds/requests",
  "requestBody": "PatronHoldPost(recordType=i, recordNumber=1316348, pickupLocation=6altn, neededBy=null, numberOfCopies=null, note=Consortial Hold. tno=83b4a431-eb46-49b6-99b2-28e60a800b63 \nFor [26998000593538]@6altn\n Pickup Altoona (IA) Public@6altn)",
  "responseBody": {
    "code": 132,
    "name": "XCirc error",
    "httpStatus": 500,
    "description": "This record is not available",
    "specificCode": 2
  },

Investigating cause and resolution – in progress