apache/flink · error · java.lang.IllegalArgumentException

Invalid JSON schema.

Error message

Invalid JSON schema.

What it means

Error "Invalid JSON schema." thrown in apache/flink.

Source

Thrown at flink-formats/flink-json/src/main/java/org/apache/flink/formats/json/JsonRowSchemaConverter.java:110

     * Converts a JSON schema into Flink's type information. Throws an exception if the schema
     * cannot converted because of loss of precision or too flexible schema.
     *
     * <p>The converter can resolve simple schema references to solve those cases where entities are
     * defined at the beginning and then used throughout a document.
     */
    @SuppressWarnings("unchecked")
    public static <T> TypeInformation<T> convert(String jsonSchema) {
        Preconditions.checkNotNull(jsonSchema, "JSON schema");
        final ObjectMapper mapper = JacksonMapperFactory.createObjectMapper();
        mapper.getFactory()
                .enable(JsonParser.Feature.ALLOW_COMMENTS)
                .enable(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES)
                .enable(JsonParser.Feature.ALLOW_SINGLE_QUOTES);
        final JsonNode node;
        try {
            node = mapper.readTree(jsonSchema);
        } catch (IOException e) {
            throw new IllegalArgumentException("Invalid JSON schema.", e);
        }
        return (TypeInformation<T>) convertType("<root>", node, node);
    }

    private static TypeInformation<?> convertType(String location, JsonNode node, JsonNode root) {
        // we use a set here to unify types (e.g. types that just add metadata such as 'multipleOf')
        final Set<TypeInformation<?>> typeSet = new HashSet<>();

        // search for ref
        final Optional<JsonNode> ref;
        if (node.has(REF) && node.get(REF).isTextual()) {
            // try a simple ref resolver to solve those cases where entities are defined at
            // the beginning and then used throughout a document
            ref = Optional.of(resolveReference(node.get(REF).asText(), node, root));
        } else {
            ref = Optional.empty();
        }

View on GitHub (pinned to 2f3c205e92)

Solutions

1. Address the cause reported by the error message: Invalid JSON schema.
2. Verify the inputs, configuration values, and classpath/dependency setup related to this operation, then retry.

Example fix

Correct the condition described ("Invalid JSON schema.") and rerun the job or command.

When it happens

Trigger: Triggered at runtime when the operation fails because: Invalid JSON schema.

Common situations: Commonly caused by misconfiguration, missing dependencies or files, unsupported types or operations, or invalid user input leading to: Invalid JSON schema.

Understand the failure class

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

AI-assisted analysis of apache/flink@2f3c205e92 (2026-08-14). Data as JSON: /api/errors/a6f48f776c1e5c09. Report an issue: GitHub.