Failed to build json for alias request – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch fails to construct a JSON object for an alias request. This could be due to incorrect syntax, missing or invalid data. To resolve this issue, you should first verify the syntax of your JSON object. Ensure that all necessary fields are included and that the data types are correct. If the error persists, check the Elasticsearch logs for more detailed error messages. It might also be helpful to validate your JSON object using a JSON validator before sending the request.

This guide will help you check for common problems that cause the log ” Failed to build json for alias request ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: alias, metadata, request, cluster.

Log Context

Log “Failed to build json for alias request” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 try {
 this.filter = new CompressedXContent(filter);
 return this;
 } catch (IOException e) {
 throw new ElasticsearchGenerationException("Failed to build json for alias request"; e);
 }  public Builder routing(String routing) {
 this.indexRouting = routing;


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