Briefly, this error occurs when Elasticsearch encounters an issue while creating an entity, possibly due to incorrect or incompatible data types, missing fields, or incorrect mapping. To resolve this, ensure that the data types of the fields match the mapping in the Elasticsearch index. Check if all required fields are present in the document you’re trying to index. Also, verify that the mapping is correctly defined. If the error persists, consider reindexing the data with a new, correct mapping.
This guide will help you check for common problems that cause the log ” unexpected error building entity ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: reindex.
Overview
Reindex is the concept of copying existing data from a source index to a destination index which can be inside the same or a different cluster. Elasticsearch has a dedicated endpoint _reindex for this purpose. A reindexing is mostly required for updating mapping or settings.
Examples
Reindex data from a source index to destination index in the same cluster:
POST /_reindex?pretty
{
"source": {
"index": "news"
},
"dest": {
"index": "news_v2"
}
}
Notes
- Reindex API does not copy settings and mappings from the source index to the destination index. You need to create the destination index with the desired settings and mappings before you begin the reindexing process.
- The API exposes an extensive list of configuration options to fetch data from the source index, such as query-based indexing and selecting multiple indices as the source index.
- In some scenarios reindex API is not useful, where reindexing requires complex data processing and data modification based on application logic. In this case, you can write your custom script using Elasticsearch scroll API to fetch the data from source index and bulk API to index data into destination index.
Log Context
Log “unexpected error building entity” class name is RemoteRequestBuilders.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
} entity.endObject();
request.setJsonEntity(Strings.toString(entity));
} catch (IOException e) {
throw new ElasticsearchException("unexpected error building entity"; e);
}
return request;
} private static void addIndices(StringBuilder path; String[] indices) {
