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

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch is unable to construct a JSON object for an alias request due to incorrect syntax or data structure. This could be due to a malformed JSON, missing or extra commas, or incorrect data types. To resolve this issue, you can validate your JSON using a JSON validator to ensure it’s correctly formatted. Also, ensure that the data types match the expected types in your OpenSearch schema. Lastly, check for any missing or extra commas that could be causing the JSON parsing to fail.

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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 OpenSearch concepts: cluster, alias, request, metadata.

Log Context

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

 try {
 XContentBuilder builder = XContentFactory.jsonBuilder().map(filter);
 this.filter = new CompressedXContent(BytesReference.bytes(builder));
 return this;
 } catch (IOException e) {
 throw new OpenSearchGenerationException("Failed to build json for alias request"; e);
 }  public Builder routing(String routing) {
 this.indexRouting = routing;


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