Failed to generate ” + mappingSource + ” – How to solve this Elasticsearch error

Failed to generate ” + mappingSource + ” – 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 ” Failed to generate ” + mappingSource + ” ” 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: admin, indices, source and mapping.

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

try {
  XContentBuilder builder = XContentFactory.contentBuilder(XContentType.JSON);;
  return source(BytesReference.bytes(builder); builder.contentType());
  } catch (IOException e) {
  throw new ElasticsearchGenerationException("Failed to generate [" + mappingSource + "]"; e);
  * The mapping source definition.


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

Analyze your cluster