Must be a valid number but was – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 8.7-8.9

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Briefly, this error occurs when Elasticsearch expects a numerical value for a specific field or parameter, but receives a non-numerical value instead. This could be due to incorrect data types in the input or a wrong query. To resolve this, ensure that the input data is of the correct numerical type. If it’s a query issue, check the query syntax and make sure numerical fields are not quoted. Also, validate your data before indexing to prevent such errors.

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This guide will help you check for common problems that cause the log ” {} must be a valid number but was [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: .

Log Context

Log “{} must be a valid number but was [{}]” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 static {
 var cacheSizeStr = System.getProperty(CACHE_CAPACITY_SETTING; "256");
 try {
 INSTANCE = new Cache(Integer.parseInt(cacheSizeStr));
 } catch (NumberFormatException e) {
 throw new SettingsException("{} must be a valid number but was [{}]"; CACHE_CAPACITY_SETTING; cacheSizeStr);
 private final ConcurrentMap>> map;
 private final int capacity;


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