Scripting Regular expression considered too many characters – How to solve this OpenSearch exception

Opster Team

Aug-23, Version: 1-1.1

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Briefly, this error occurs when a regular expression (regex) in a script is too complex or large, causing OpenSearch to exceed its set limit of characters it can process. This is a safeguard to prevent potential Denial of Service (DoS) attacks. To resolve this issue, you can either simplify your regex or split it into smaller parts. Alternatively, you can increase the limit of characters OpenSearch can process, but be cautious as this may make your system vulnerable to DoS attacks.

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This guide will help you check for common problems that cause the log ” [scripting] Regular expression considered too many characters; ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: .

Log Context

Log “[scripting] Regular expression considered too many characters;” class name is We extracted the following from OpenSearch source code for those seeking an in-depth context :

 public char charAt(int index) {
 if (counter.hitLimit()) {
 throw new CircuitBreakingException("[scripting] Regular expression considered too many characters; " + details() +
 "; this limit can be changed by changed by the [" + CompilerSettings.REGEX_LIMIT_FACTOR.getKey() + "] setting";
 return wrapped.charAt(index);


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