spring-projects/spring-ai · error · RuntimeException

Failed to parse JSON:

Error message

Failed to parse JSON: 

What it means

JsonSchemaConverter.fromJson(jsonString) parses a JSON string into a Jackson ObjectNode using the shared mapper; any parse/IO exception is rethrown as a RuntimeException with the offending string in the message. The library throws this when the supplied text is not valid JSON.

Source

Thrown at models/spring-ai-google-genai/src/main/java/org/springframework/ai/google/genai/schema/JsonSchemaConverter.java:54

 */
public final class JsonSchemaConverter {

	private JsonSchemaConverter() {
		// Prevent instantiation
	}

	/**
	 * Parses a JSON string into an ObjectNode.
	 * @param jsonString The JSON string to parse
	 * @return ObjectNode containing the parsed JSON
	 * @throws RuntimeException if the JSON string cannot be parsed
	 */
	public static ObjectNode fromJson(String jsonString) {
		try {
			return (ObjectNode) JacksonUtils.getDefaultJsonMapper().readTree(jsonString);
		}
		catch (Exception e) {
			throw new RuntimeException("Failed to parse JSON: " + jsonString, e);
		}
	}

	/**
	 * Converts a JSON Schema ObjectNode to OpenAPI schema format.
	 * @param jsonSchemaNode The input JSON Schema as ObjectNode
	 * @return ObjectNode containing the OpenAPI schema
	 * @throws IllegalArgumentException if jsonSchemaNode is null
	 */
	public static ObjectNode convertToOpenApiSchema(ObjectNode jsonSchemaNode) {
		Assert.notNull(jsonSchemaNode, "JSON Schema node must not be null");
		Assert.isTrue(!jsonSchemaNode.has("$defs"), "Google's Structured Output schema doesn't support $defs property");

		try {
			// Convert to OpenAPI schema using our custom conversion logic
			ObjectNode openApiSchema = convertSchema(jsonSchemaNode,
					JacksonUtils.getDefaultJsonMapper().getNodeFactory());

View on GitHub (pinned to 98a7beda4f)

Solutions

1. Validate the JSON string with a linter/parser before passing it in
2. Trim whitespace and remove non-JSON prefixes/suffixes (e.g., markdown fences from LLM output)
3. Confirm the string is not empty or truncated
4. Catch RuntimeException and surface the failing input for debugging

Example fix

// before
ObjectNode schema = JsonSchemaConverter.fromJson(raw);
// after
String cleaned = raw.strip().replaceAll("^```(json)?|```$", "");
ObjectNode schema = JsonSchemaConverter.fromJson(cleaned);

if (json == null || json.isBlank()) {
    throw new IllegalArgumentException("empty JSON input");
}
try (var p = new java.io.StringReader(json)) {
    new com.fasterxml.jackson.core.JsonFactory().createParser(p).close(); // cheap syntax probe
}

boolean isProbablyJson(String s) {
    if (s == null) return false;
    String t = s.strip();
    return (t.startsWith("{") && t.endsWith("}")) || (t.startsWith("[") && t.endsWith("]"));
}

try {
    ObjectNode node = JsonSchemaConverter.fromJson(json);
} catch (RuntimeException e) {
    logger.error("bad schema input: {}", e.getMessage());
    throw new IllegalArgumentException("schema must be valid JSON", e);
}

When it happens

Trigger: Calling fromJson with malformed JSON, empty/blank input, or JSON that fails to read (e.g., trailing garbage, unquoted keys).

Common situations: Hand-written JSON Schemas pasted into code, schemas read from files/LLM output with stray text, or truncation of large schema strings.

Understand the failure class

Background: JSON parse error: "Unexpected token" / "not valid JSON" / "failed to parse" — what JSON parsers are really complaining about — this error's family across 45 libraries.

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

Related errors

• JacksonException (wrapped IllegalStateException)
• Error parsing JSON-RPC message:
• Failed to parse JSON:
• Cannot deserialize ThinkOption from token:
• Failed to parse JSON schema

AI-assisted analysis of spring-projects/spring-ai@98a7beda4f (2026-09-11). Data as JSON: /api/errors/3f109b3e7193d88d. Report an issue: GitHub.