Invalid operation mode in %s – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8.4-8.7

Briefly, this error occurs when Elasticsearch encounters an invalid operation mode in its settings. This could be due to a misconfiguration or an unsupported operation mode. To resolve this issue, you should first verify the operation mode in your Elasticsearch configuration. Ensure that it is set to a valid mode supported by your version of Elasticsearch. If the error persists, consider updating or reinstalling Elasticsearch to ensure that all components are functioning correctly. Lastly, check your Elasticsearch logs for more detailed error messages that can help pinpoint the issue.

This guide will help you check for common problems that cause the log ” invalid operation mode in [%s] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin, license.

Log Context

Log “invalid operation mode in [%s]” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                    // this UTF-8 conversion is much pickier than java String
                    final String operationMode = new BytesRef(content).utf8ToString();
                    try {
                        newOperationMode = OperationMode.parse(operationMode);
                    } catch (IllegalArgumentException e) {
                        logger.error(() -> format("invalid operation mode in [%s]"; licenseModePath.toAbsolutePath()); e);
            } finally {
                // set this after the fact to prevent that we are jumping back and forth first setting to default and then reading the