Failed to derive type – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch is unable to determine the data type of a field during indexing. This could be due to incorrect mapping or incompatible data types. To resolve this issue, you can explicitly define the mapping for the field in question, ensuring the data type matches the data you’re trying to index. Alternatively, you can modify the data to match the existing mapping. If the error persists, consider reindexing your data with the correct mapping.

This guide will help you check for common problems that cause the log ” Failed to derive type ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index.

Log Context

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

 type = rootName;
 mapping = (Map) mapping.get(rootName);
 if (type == null) {
 throw new MapperParsingException("Failed to derive type");
 if (type.isEmpty()) {
 throw new MapperParsingException("type cannot be an empty string");
 return parse(type; mapping);