I recently upgraded my application to Spring Boot 3.1.4, Java 21, and Hibernate 6.2.9. Since the upgrade, I am encountering the following error when trying to save JSON data into my database:

WARN 1 — [erContainer#0-2] o.h.engine.jdbc.spi.SqlExceptionHelper
: SQL Error: 3144, SQLState: 22001
Data truncation: Cannot create a JSON value from a string with CHARACTER SET ‘binary’.

Here is the relevant code where the exception occurs:

@Service
public class JpaDataWritingServiceImpl implements DataWritingService {
    @Autowired
    TestDataRepository testDataRepository;
    @Autowired
    TestRepository testRepository;

    @Override
    public void writetestData(Long testId, String type, byte[] data, testStatus testStatus, boolean needsBackgroundtest) {
        Optional<Test> maybeTest = testRepository.findById(testId);
        if (maybeTest.isPresent()) {
            Test test = maybeTest.get();
            String metadata = generateMetadataForTestData(data);

            TestData testData = new TestData(test, type, data, metadata);

            LOG.debug("Saving TestData======> data={}, metadata={}", dataString, metadata); // To verify data before save() --> for

            testDataRepository.save(new TestData(test, type, data, metadata)); // Fails here
        } else {
            LOG.warn("Didn't find testData with id {}", testId);
        }
    }

    private String generateMetadataForTestData(byte[] data) {
        String byteToStringData = new String(data, StandardCharsets.UTF_8);
        JSONObject byteToString = new JSONObject(byteToStringData);
        JSONObject stringToJson = new JSONObject();

        if (byteToString.has("platform")) {
            stringToJson.put("content_id", byteToString.getString("id"));
            try {
                Date date = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(byteToString.getString("timestamp"));
                long epochTime = date.getTime() / 1000;
                stringToJson.put("timestamp", epochTime);
            } catch (ParseException e) {
                LOG.error("DateTime parse exception: {}", e.getMessage());
            }
        }
        return stringToJson.length() == 0 ? null : stringToJson.toString();
    }
}

Error Stack Trace
Here is the error I am receiving:

Caused by: org.springframework.dao.DataIntegrityViolationException: could not execute statement [Data truncation: Cannot create a JSON value from a string with CHARACTER SET ‘binary’.]
[insert into test_data (test_id, data, metadata, received_at, type) values (?,?,?,?,?)]

Entity Definition
Here is the CampaignData entity:

@Entity
@Table(name="test_data")
public class TestData {

    public TestData(){}

    public TestData(Test test,
                        String type,
                        byte[] data,
                        String metadata) {
        this.test = test;
        this.type = type;
        this.data = data;
        this.metadata = metadata;
        this.receivedAt = Instant.now();
    }

    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @ManyToOne private Test test;

    private String type;

    @NotNull @Lob
    private byte[] data;

    @JsonIgnore
    @OneToOne(cascade = CascadeType.ALL, mappedBy = "testData")
    private TestDataTestStatus testStatus;

    @Column(name = "received_at")
    private Instant receivedAt;

    @Lob
    @Column(columnDefinition = "json")
    private String metadata;

    // Other fields and getters/setters...
}

Database Configuration:

CREATE TABLE `test_data` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `test_id` bigint NOT NULL,
  `data` mediumblob NOT NULL,
  `received_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `type` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci DEFAULT NULL,
  `metadata` json DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `fk_test_data_test` (`test_id`),
  CONSTRAINT `fk_test_data_test` FOREIGN KEY (`test_id`) REFERENCES `test` (`id`) ON DELETE RESTRICT ON UPDATE RESTRICT
) ENGINE=InnoDB AUTO_INCREMENT=175613200 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_as_ci

Observations

•   The same code worked before the upgrade.
•   The data field contains JSON data serialized as byte[], which I convert to String and store in the metadata column.
•   The application log shows that data and metadata are valid JSON strings:

Saving testData======> data={"id":"113662220040053124", ...}, metadata={"content_id":"113662220040053124","timestamp":1734347839}

Questions

1. Why am I getting a CHARACTER SET ‘binary’ error when saving the JSON metadata or byte[] data now?
2. Is there a new requirement in Hibernate 6.2.x or Spring Boot 3.1.x for handling JSON or byte[] fields?