Pattern must not be null – How to solve this Elasticsearch error

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Pattern must not be null – 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 Error Check-Up which can resolve issues that cause many errors.

This guide will help you check for common problems that cause the log ” Pattern must not be null ” to appear. It’s important to understand the issues related to the log, so to get started, read the general overview on common issues and tips related to the Elasticsearch concepts: parser and plugin.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to pinpoint the cause of many errors and provides suitable actionable recommendations how to resolve them (free tool that requires no installation).

Log Context

Log”Pattern must not be [null]”classname  is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

return null;
  String pattern = string(ctx.value);
  if (pattern == null) {
  throw new ParsingException(source(ctx.value); "Pattern must not be [null]");
  int pos = pattern.indexOf('*');
  if (pos >= 0) {
  throw new ParsingException(source(ctx.value);
  "Invalid char [*] found in pattern [{}] at position {}; use [%] or [_] instead";


Run the Check-Up to get a customized report like this:

Analyze your cluster