Unknown month number – Elasticsearch Error How To Solve Related Issues

Unknown month number – Elasticsearch Error How To Solve Related Issues

Updated: July-20

Elasticsearch Version: 1.7-8.0

Before you begin reading this guide, we recommend you try running the Elasticsearch Error Check-Up  which can resolve issues causing many errors 


This guide will help you check for common problems that cause the log “unknown month number” to appear. It’s important to understand the issues related to the log, so to get started, read the general overview on common issues and tips related to the Elasticsearch concepts: plugin.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to discover the cause of many errors and provides suitable actionable recommendations (free tool that requires no installation). 

Log Context

Log”unknown month number [{}]”classname  is Month.java
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

case 9: return SEPTEMBER;
  case 10: return OCTOBER;
  case 11: return NOVEMBER;
  case 12: return DECEMBER;
  throw new ElasticsearchParseException("unknown month number [{}]"; month);
  public static Month resolve(String day) {
  switch (day.toLowerCase(Locale.ROOT)) {

Related issues to this log

We have gathered selected Q&A from the community and issues from Github, that can help fix related issues please review the following for further information :

1 ElasticSearch: script inline subtract dates -views 534 

Can't map date correctly with elasticsearch + kibana + twitter -views   166

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