Invalid action name actionName must start with one of – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when the action name you’re trying to execute in OpenSearch doesn’t start with a predefined prefix. OpenSearch requires certain prefixes for action names to ensure they’re valid and can be executed properly. To resolve this issue, you should check the action name you’re using and ensure it starts with one of the allowed prefixes. If it doesn’t, you should change the action name to start with a valid prefix. If you’re unsure of the valid prefixes, refer to the OpenSearch documentation or your OpenSearch configuration.

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This guide will help you check for common problems that cause the log ” invalid action name [” + actionName + “] must start with one of: ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: .

Log Context

Log “invalid action name [” + actionName + “] must start with one of: ” classname is
We extracted the following from OpenSearch source code for those seeking an in-depth context :

    private void validateActionName(String actionName) {
        // TODO we should makes this a hard validation and throw an exception but we need a good way to add backwards layer
        // for it. Maybe start with a deprecation layer
        if (isValidActionName(actionName) == false) {
            logger.warn("invalid action name [" + actionName + "] must start with one of: " + TransportService.VALID_ACTION_PREFIXES);

     * Returns true iff the action name starts with a valid prefix.


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