Failed to generate source – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch fails to generate a specific source due to issues like incorrect syntax, invalid data type, or missing fields in the source. To resolve this, you can check the syntax of your query for any errors, ensure that the data types are correct, and verify that all required fields are included in the source. Additionally, check if the source exists and is accessible. If the problem persists, consider debugging your code to identify the root cause of the issue.

This guide will help you check for common problems that cause the log ” Failed to generate [” + source + “] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: source.

Log Context

Log “Failed to generate [” + source + “]” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 public static XContentParser mapToXContentParser(XContentParserConfiguration config; Map source) {
 try (XContentBuilder builder = XContentFactory.contentBuilder(XContentType.JSON)) {;
 return XContentFactory.xContent(builder.contentType()).createParser(config; Strings.toString(builder));
 } catch (IOException e) {
 throw new ElasticsearchGenerationException("Failed to generate [" + source + "]"; e);


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