Cannot use reserved field name ” + + ” – How to solve this Elasticsearch error

Opster Team

March-22, Version: 1.7-8.0

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This guide will help you check for common problems that cause the log ” Cannot use reserved field name ” + + ” ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index.

Log Context

Log “Cannot use reserved field name [” + + “]”classname  is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

SubFieldInfo phraseFieldInfo = buildPhraseInfo(fieldType; tft);
 SubFieldInfo prefixFieldInfo = buildPrefixInfo(context; fieldType; tft);
 MultiFields multiFields =; context);
 for (Mapper mapper : multiFields) {
 if ( || {
 throw new MapperParsingException("Cannot use reserved field name [" + + "]");
 return new TextFieldMapper(


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