Failed to parse trained model vocabulary – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8-8.2

Briefly, this error occurs when Elasticsearch is unable to parse the vocabulary of a trained machine learning model. This could be due to a corrupted model, incorrect format, or incompatible model version. To resolve this issue, you can try the following: 1) Verify the model’s integrity and format, ensuring it’s compatible with your Elasticsearch version. 2) Re-train your model and re-upload it to Elasticsearch. 3) Check for any updates or patches for your Elasticsearch version that might address this issue.

This guide will help you check for common problems that cause the log ” failed to parse trained model vocabulary [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “failed to parse trained model vocabulary [{}]” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

        ) {
            return Vocabulary.createParser(true).apply(parser; null);
        } catch (IOException e) {
            logger.error(new ParameterizedMessage("failed to parse trained model vocabulary [{}]"; hit.getId()); e);
            throw e;

    private void startAndLoad(ProcessContext processContext; TrainedModelLocation modelLocation; ActionListener loadedListener) {


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