What causes "Invalid JSON file '%s' for '%s'" in prestodb/presto?

Verify the file path exists and is readable by the Presto process user

prestodb/presto · error · IllegalArgumentException

Invalid JSON file '%s' for '%s'

Error message

Invalid JSON file '%s' for '%s'

What it means

JsonUtils.parseJson reads a file fully into memory and deserializes it into javaType via Jackson with FAIL_ON_UNKNOWN_PROPERTIES enabled. Any IOException — unreadable file, malformed JSON, or a type mismatch surfaced as an IO failure — becomes an IllegalArgumentException naming the path and target type.

Source

Thrown at presto-plugin-toolkit/src/main/java/com/facebook/presto/plugin/base/JsonUtils.java:49

    private JsonUtils() {}

    public static <T> T parseJson(Path path, Class<T> javaType)
    {
        if (!path.isAbsolute()) {
            path = path.toAbsolutePath();
        }

        checkArgument(exists(path), "File does not exist: %s", path);
        checkArgument(isReadable(path), "File is not readable: %s", path);

        try {
            byte[] json = Files.readAllBytes(path);
            ObjectMapper mapper = new JsonObjectMapperProvider().get()
                    .enable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
            return mapper.readValue(json, javaType);
        }
        catch (IOException e) {
            throw new IllegalArgumentException(format("Invalid JSON file '%s' for '%s'", path, javaType), e);
        }
    }
}

View on GitHub (pinned to 55bb57d202)

Solutions

Verify the file path exists and is readable by the Presto process user
Validate the JSON with a linter (jq < file) to find syntax errors
Compare the JSON fields against the target Java type; remove unknown or renamed properties
Check whether a version upgrade changed the expected schema for this file

Example fix

// before
return mapper.readValue(json, javaType); // throws on unknown props
// after
ObjectMapper mapper = new JsonObjectMapperProvider().get()
        .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
return mapper.readValue(json, javaType);

Defensive patterns

Strategy: validation

Validate before calling

# shell pre-check before pointing the plugin at the file
jq empty /etc/presto/my-config.json && test -r /etc/presto/my-config.json && echo OK

Try / catch

try {
    MyConfig cfg = JsonUtils.parseJson(path, MyConfig.class);
} catch (IllegalArgumentException e) {
    log.error("bad JSON config " + path, e.getCause());
    throw e;
}

Prevention

Run jq/yamllint-style validation in deployment scripts before restart
Keep config JSON under schema validation in CI
Ensure the Presto process user has read access to config files
Diff config fields against the expected type after upgrades

When it happens

Trigger: parseJson(path, javaType) is given a path that does not exist or is unreadable, or a file whose content is not valid JSON, or JSON that Jackson cannot map to the requested type while FAIL_ON_UNKNOWN_PROPERTIES is enabled.

Common situations: Typos in the JSON rules/policy file path in plugin config; hand-edited JSON with a trailing comma; config schema drift after a version upgrade added/renamed fields.

Understand the failure class

Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/73476c5883730f8c. Report an issue: GitHub.