Loading extension has been failed because of exception – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 2.8-2.9

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Briefly, this error occurs when OpenSearch fails to load an extension due to an exception. This could be due to a variety of reasons such as incorrect configuration, missing dependencies, or compatibility issues. To resolve this, you can try the following: 1) Check the extension’s configuration and ensure it’s correct. 2) Verify that all required dependencies are installed and up-to-date. 3) Ensure the extension is compatible with your version of OpenSearch. 4) If the error persists, consider removing and reinstalling the extension.

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This guide will help you check for common problems that cause the log ” loading extension has been failed because of exception : ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: rest.

Log Context

Log “loading extension has been failed because of exception :” classname is RestInitializeExtensionAction.java.
We extracted the following from OpenSearch source code for those seeking an in-depth context :

            version = extensionMap.get("version").toString();
            openSearchVersion = extensionMap.get("opensearchVersion").toString();
            minimumCompatibleVersion = extensionMap.get("minimumCompatibleVersion").toString();
            dependencies = extensionDependencyList;
        } catch (IOException e) {
            logger.warn("loading extension has been failed because of exception : " + e.getMessage());
            return channel -> channel.sendResponse(new BytesRestResponse(RestStatus.INTERNAL_SERVER_ERROR; e.getMessage()));

        Extension extension = new Extension(


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