baomidou/mybatis-plus · critical · IOException

Failed getting a databaseId

Error message

Failed getting a databaseId

What it means

Thrown by MybatisSqlSessionFactoryBean.buildSqlSessionFactory during Spring SqlSessionFactory bootstrap: when a databaseIdProvider is configured, it calls databaseIdProvider.getDatabaseId(dataSource), and a SQLException from that probe is wrapped in IOException('Failed getting a databaseId') so startup fails fast. The SQLException cause identifies the real connectivity or provider problem.

Source

Thrown at mybatis-plus-spring/src/main/java/com/baomidou/mybatisplus/spring/MybatisSqlSessionFactoryBean.java:650

            });
        }

        targetConfiguration.setDefaultEnumTypeHandler(defaultEnumTypeHandler);

        if (!isEmpty(this.scriptingLanguageDrivers)) {
            Stream.of(this.scriptingLanguageDrivers).forEach(languageDriver -> {
                targetConfiguration.getLanguageRegistry().register(languageDriver);
                LOGGER.debug(() -> "Registered scripting language driver: '" + languageDriver + "'");
            });
        }
        Optional.ofNullable(this.defaultScriptingLanguageDriver)
            .ifPresent(targetConfiguration::setDefaultScriptingLanguage);

        if (this.databaseIdProvider != null) {// fix #64 set databaseId before parse mapper xmls
            try {
                targetConfiguration.setDatabaseId(this.databaseIdProvider.getDatabaseId(this.dataSource));
            } catch (SQLException e) {
                throw new IOException("Failed getting a databaseId", e);
            }
        }

        Optional.ofNullable(this.cache).ifPresent(targetConfiguration::addCache);

        if (xmlConfigBuilder != null) {
            try {
                xmlConfigBuilder.parse();
                LOGGER.debug(() -> "Parsed configuration file: '" + this.configLocation + "'");
            } catch (Exception ex) {
                throw new IOException("Failed to parse config resource: " + this.configLocation, ex);
            } finally {
                ErrorContext.instance().reset();
            }
        }

        targetConfiguration.setEnvironment(new Environment(this.environment,
            this.transactionFactory == null ? new SpringManagedTransactionFactory() : this.transactionFactory,

View on GitHub (pinned to bf67d90747)

Solutions

1. Check the wrapped SQLException cause for the concrete JDBC failure and fix connectivity/credentials/driver
2. Verify the DataSource bean the factory uses points at a reachable database (test with a plain Connection in a breakpoint or health check)
3. In orchestrated environments, ensure the database is a startup dependency (depends-on, container healthchecks) or remove databaseIdProvider if databaseId is not actually used
4. If mapper XMLs use databaseId, confirm the provider is configured with correct properties (e.g. VendorDatabaseIdProvider 'Oracle'->'oracle' mappings)

Example fix

// before: factory initializes while DB is down
@Bean
public SqlSessionFactory sqlSessionFactory(DataSource ds) throws Exception {
  MybatisSqlSessionFactoryBean factory = new MybatisSqlSessionFactoryBean();
  factory.setDataSource(ds);
  factory.setDatabaseIdProvider(new VendorDatabaseIdProvider());
  return factory.getObject();
}
// after: only set provider when it is actually needed, after DB is reachable
factory.setDatabaseIdProvider(databaseIdUsed ? new VendorDatabaseIdProvider() : null);

// Fail fast with a clear message before building the factory
try (Connection ignored = dataSource.getConnection()) {
    // DB reachable
} catch (SQLException e) {
    throw new IllegalStateException("Database unreachable; cannot resolve databaseId", e);
}

try {
    sqlSessionFactory(bean).getObject();
} catch (IOException e) {
    if ("Failed getting a databaseId".equals(e.getMessage())) {
        // inspect e.getCause() SQLException; verify DB URL/credentials/startup order
        throw new IllegalStateException("databaseIdProvider could not reach the database", e.getCause());
    }
    throw e;
}

When it happens

Trigger: Setting the databaseIdProvider property on MybatisSqlSessionFactoryBean (mybatis-plus-spring) while the DataSource cannot serve the provider's metadata query — DB down, wrong URL/credentials, driver missing, or a custom VendorDatabaseIdProvider whose getDatabaseName query fails.

Common situations: Application startup order issues where the bean initializes before the DB is reachable (containers/K8s); credentials rotated and not updated; using databaseIdProvider for multi-dialect mapper support and the connection URL is misconfigured.

Related errors

• Failed to parse config resource:
• Failed to parse mapping resource: '
• 获取自定义字段错误:
• 读取[%s]字段出错!
• connection cannot be null

AI-assisted analysis of baomidou/mybatis-plus@bf67d90747 (2026-08-14). Data as JSON: /api/errors/8b35b0aea8798ca0. Report an issue: GitHub.