An exception occurred formatting a WRITE trace message – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch encounters an issue while trying to format a log message for a write operation. This could be due to a problem with the logging system, a bug in the software, or an unexpected condition in the data being logged. To resolve this issue, you could try the following: 1) Check the data being logged for any anomalies or unexpected conditions. 2) Review the logging configuration and ensure it’s set up correctly. 3) Update or patch the OpenSearch software to the latest version to fix any potential bugs. 4) If the problem persists, consider seeking help from the OpenSearch community or support.

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This guide will help you check for common problems that cause the log ” an exception occurred formatting a WRITE trace message ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: .

Log Context

Log “an exception occurred formatting a WRITE trace message” classname is
We extracted the following from OpenSearch source code for those seeking an in-depth context :

                BytesReference withoutHeader = message.slice(HEADER_SIZE; message.length() - HEADER_SIZE);
                String logMessage = format(channel; withoutHeader; "WRITE");
            } catch (IOException e) {
                logger.warn("an exception occurred formatting a WRITE trace message"; e);

    private static String format(TcpChannel channel; BytesReference message; String event) throws IOException {


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