Should be a hash but was of type – How to solve this OpenSearch exception

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch expects a hash data type but encounters a different data type. This could be due to incorrect data input or a mismatch in the expected data structure. To resolve this, ensure that the input matches the expected hash data structure. Check your data input or the code where the data is being processed. If the error persists, you may need to debug your code to identify where the mismatch is occurring.

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This guide will help you check for common problems that cause the log ” should be a hash but was of type: ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: .

Log Context

Log “should be a hash but was of type:” class name is We extracted the following from OpenSearch source code for those seeking an in-depth context :

 public static Map nodeMapValue(Object node; String desc) {
 if (node instanceof Map) {
 return (Map) node;
 } else {
 throw new OpenSearchParseException(desc + " should be a hash but was of type: " + node.getClass());
 }  /**
 * Returns an array of string value from a node value.


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