Unicode sequence should use 2-8 hex digits has – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 7.13-7.15

Briefly, this error occurs when Elasticsearch encounters a Unicode sequence that doesn’t meet the required length of 2-8 hex digits. This could be due to incorrect formatting or encoding of data. To resolve this issue, you can: 1) Check the data being indexed for any incorrectly formatted Unicode sequences and correct them. 2) Ensure that the data is properly encoded before indexing. 3) If you’re using a script or tool to generate or manipulate data, verify that it’s handling Unicode sequences correctly.

This guide will help you check for common problems that cause the log ” Unicode sequence should use [2-8] hex digits; [{}] has [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin, parser.

Log Context

Log “Unicode sequence should use [2-8] hex digits; [{}] has [{}]” class name is AbstractBuilder.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 int startIdx = i + 1;
 int endIdx = text.indexOf('}'; startIdx);
 unicodeSequence = text.substring(startIdx; endIdx);
 int length = unicodeSequence.length();
 if (length < 2 || length > 8) {
 throw new ParsingException(source; "Unicode sequence should use [2-8] hex digits; [{}] has [{}]";
 text.substring(startIdx - 3; endIdx + 1); length);
 sb.append(hexToUnicode(source; unicodeSequence));
 return endIdx;


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