Unknown array – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-7.13

Briefly, this error occurs when Elasticsearch encounters an array with an unexpected or unknown format in the request body. This could be due to a malformed request or a mismatch between the data structure and the expected schema. To resolve this issue, you can: 1) Review the request body to ensure the array is correctly formatted. 2) Check the Elasticsearch schema to ensure it matches the data structure. 3) Update the Elasticsearch schema if it doesn’t match the data structure. 4) Validate the data before sending it to Elasticsearch to prevent malformed requests.

This guide will help you check for common problems that cause the log ” unknown array [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index, blobstore.

Log Context

Log “unknown array [{}]” class name is BlobStoreIndexShardSnapshots.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 XContentParserUtils.ensureExpectedToken(XContentParser.Token.FIELD_NAME; token; parser);
 String currentFieldName = parser.currentName();
 token = parser.nextToken();
 if (token == XContentParser.Token.START_ARRAY) {
 if (ParseFields.FILES.match(currentFieldName; parser.getDeprecationHandler()) == false) {
 throw new ElasticsearchParseException("unknown array [{}]"; currentFieldName);
 while (parser.nextToken() != XContentParser.Token.END_ARRAY) {
 FileInfo fileInfo = FileInfo.fromXContent(parser);
 files.put(fileInfo.name(); fileInfo);