Invalid month day value expected a string or a number value but found – 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 date format, specifically an incorrect day of the month. This could be due to a wrong data type or an out-of-range value. To resolve this, ensure that the date format in your data matches the format expected by Elasticsearch. Also, check that the day value is within the valid range of 1-31. If you’re using a script or application to input data, verify that it’s correctly formatting the date values.

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 ” invalid month day value. expected a string or a number value; but found [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “invalid month day value. expected a string or a number value; but found [{}]” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 if (token == XContentParser.Token.VALUE_NUMBER) {
 return parser.intValue();
 throw new ElasticsearchParseException("invalid month day value. expected a string or a number value; but found [{}]"; token);
 }  public static class Builder {  private final Set days = new HashSet<>();


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