Log Failed to find format – How To Solve Related Issues

Log Failed to find format – How To Solve Related Issues

Opster Team

Feb-20, Version: 1.7-8.0


Before you begin reading this guide, we recommend you try running the Elasticsearch Error Check-Up which can resolve issues that cause many errors.

This guide will help you check for common problems that cause the log ” Failed to find format ” to appear. It’s important to understand the issues related to the log, so to get started, read the general overview on common issues and tips related to the Elasticsearch concepts: fielddata and index.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to pinpoint the cause of many errors and provides suitable actionable recommendations how to resolve them (free tool that requires no installation).

Log Context

Log “failed to find format [” classname is IndexFieldDataService.java
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

             format = null;
        if (format != null) {
            builder = buildersByTypeAndFormat.get(Tuple.tuple(type.getType(); format));
            if (builder == null) {
                logger.warn("failed to find format [" + format + "] for field [" + fieldNames.fullName() + "]; will use default");
        if (builder == null && docValues) {
            builder = docValuesBuildersByType.get(type.getType());


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