{"record":{"id":"cdaac024da95827d","repo":"elastic/elasticsearch","slug":"unknown-key-for-a-token-in-reducername-cu","errorCode":null,"errorMessage":"Unknown key for a {token} in [{reducerName}]: [{currentFieldName}].","messagePattern":"Unknown key for a (.+?) in \\[(.+?)\\]: \\[(.+?)\\]\\.","errorType":"validation","errorClass":"ParsingException","httpStatus":null,"severity":"error","filePath":"modules/aggregations/src/main/java/org/elasticsearch/aggregations/pipeline/BucketSelectorPipelineAggregationBuilder.java","lineNumber":114,"sourceCode":"        XContentParser.Token token;\n        Script script = null;\n        String currentFieldName = null;\n        Map<String, String> bucketsPathsMap = null;\n        GapPolicy gapPolicy = null;\n\n        while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {\n            if (token == XContentParser.Token.FIELD_NAME) {\n                currentFieldName = parser.currentName();\n            } else if (token == XContentParser.Token.VALUE_STRING) {\n                if (BUCKETS_PATH.match(currentFieldName, parser.getDeprecationHandler())) {\n                    bucketsPathsMap = new HashMap<>();\n                    bucketsPathsMap.put(\"_value\", parser.text());\n                } else if (GAP_POLICY.match(currentFieldName, parser.getDeprecationHandler())) {\n                    gapPolicy = GapPolicy.parse(parser.text(), parser.getTokenLocation());\n                } else if (Script.SCRIPT_PARSE_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {\n                    script = Script.parse(parser);\n                } else {\n                    throw new ParsingException(\n                        parser.getTokenLocation(),\n                        \"Unknown key for a \" + token + \" in [\" + reducerName + \"]: [\" + currentFieldName + \"].\"\n                    );\n                }\n            } else if (token == XContentParser.Token.START_ARRAY) {\n                if (BUCKETS_PATH.match(currentFieldName, parser.getDeprecationHandler())) {\n                    List<String> paths = new ArrayList<>();\n                    while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {\n                        String path = parser.text();\n                        paths.add(path);\n                    }\n                    bucketsPathsMap = new HashMap<>();\n                    for (int i = 0; i < paths.size(); i++) {\n                        bucketsPathsMap.put(\"_value\" + i, paths.get(i));\n                    }\n                } else {\n                    throw new ParsingException(\n                        parser.getTokenLocation(),","sourceCodeStart":96,"sourceCodeEnd":132,"githubUrl":"https://github.com/elastic/elasticsearch/blob/db6a809a667c081ca1dc7500389d26975573215f/modules/aggregations/src/main/java/org/elasticsearch/aggregations/pipeline/BucketSelectorPipelineAggregationBuilder.java#L96-L132","documentation":"Error \"Unknown key for a {token} in [{reducerName}]: [{currentFieldName}].\" thrown in elastic/elasticsearch.","triggerScenarios":"Thrown at modules/aggregations/src/main/java/org/elasticsearch/aggregations/pipeline/BucketSelectorPipelineAggregationBuilder.java:114 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"db6a809a667c081ca1dc7500389d26975573215f","analyzedAt":"2026-08-12T01:39:14.192Z","schemaVersion":2},"datasetVersion":"2026-08-12T12:31:55.035Z"}