Unknown day of week number – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Before you dig into reading this guide, have you tried asking OpsGPT what this log means? You’ll receive a customized analysis of your log.

Try OpsGPT now for step-by-step guidance and tailored insights into your Elasticsearch operation.

Briefly, this error occurs when Elasticsearch encounters an invalid day of week number in a date-related operation. Elasticsearch expects day of week numbers to be between 1 (Monday) and 7 (Sunday). If the number is outside this range, it throws this error. To resolve this issue, ensure that all day of week numbers in your data and queries are within the valid range. Also, check your date parsing and formatting settings to prevent incorrect conversion of dates into day of week numbers.

For a complete solution to your to your search operation, try for free AutoOps for Elasticsearch & OpenSearch . With AutoOps and Opster’s proactive support, you don’t have to worry about your search operation – we take charge of it. Get improved performance & stability with less hardware.

This guide will help you check for common problems that cause the log ” unknown day of week number [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “unknown day of week number [{}]” class name is DayOfWeek.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 case 3 -> TUESDAY;
 case 4 -> WEDNESDAY;
 case 5 -> THURSDAY;
 case 6 -> FRIDAY;
 case 7 -> SATURDAY;
 default -> throw new ElasticsearchParseException("unknown day of week number [{}]"; day);
 }  public static DayOfWeek resolve(String day) {
 return switch (day.toLowerCase(Locale.ROOT)) {


How helpful was this guide?

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?

Get expert answers on Elasticsearch/OpenSearch