Unknown array – How to solve this Elasticsearch error

Opster Team

July-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you try running the Elasticsearch Check-Up which can resolve issues that cause many errors.

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: blobstore and index.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up to analyze Elasticsearch configuration and help resolve this error.

Log Context

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

 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);


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