OpenAPITools/openapi-generator · error · RuntimeException

This library requires Spring Boot 3 or 4. Try adding '--addi

Error message

This library requires Spring Boot 3 or 4. Try adding '--additional-properties useSpringBoot3=true' or '--additional-properties useSpringBoot4=true' to your command.

What it means

processJvmSpringRestClientLibrary requires an explicit Spring Boot baseline for the jvm-spring-restclient library: the guard checks additionalProperties for useSpringBoot3 or useSpringBoot4 via getOrDefault(...,false).equals(false), so if both are absent (or both false) it throws. Spring Boot 2 or unspecified baselines are not supported for the RestClient template.

Source

Thrown at modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java:893

            throw new RuntimeException("This library currently only supports jackson serialization. Try adding '--additional-properties serializationLibrary=jackson' to your command.");
        }

        commonJvmMultiplatformSupportingFiles(infrastructureFolder);
        addSupportingSerializerAdapters(infrastructureFolder);

        additionalProperties.put(JVM_SPRING, true);
        additionalProperties.put(JVM, true);
    }

    private void processJvmSpringWebClientLibrary(final String infrastructureFolder) {
        processJvmSpring(infrastructureFolder);
        additionalProperties.put(JVM_SPRING_WEBCLIENT, true);
    }

    private void processJvmSpringRestClientLibrary(final String infrastructureFolder) {
        if (additionalProperties.getOrDefault(USE_SPRING_BOOT3, false).equals(false)
                && additionalProperties.getOrDefault(USE_SPRING_BOOT4, false).equals(false)) {
            throw new RuntimeException("This library requires Spring Boot 3 or 4. Try adding '--additional-properties useSpringBoot3=true' or '--additional-properties useSpringBoot4=true' to your command.");
        }

        processJvmSpring(infrastructureFolder);
        additionalProperties.put(JVM_SPRING_RESTCLIENT, true);
    }

    private void processMultiplatformLibrary(final String infrastructureFolder) {
        commonJvmMultiplatformSupportingFiles(infrastructureFolder);
        additionalProperties.put(MULTIPLATFORM, true);

        if (!DateLibrary.STRING.value.equals(dateLibrary) && !DateLibrary.KOTLINX_DATETIME.value.equals(dateLibrary)) {
            throw new RuntimeException("Multiplatform only supports string and kotlinx-datetime. Try adding '--additional-properties dateLibrary=kotlinx-datetime' to your command.");
        }

        setRequestDateConverter(RequestDateConverter.TO_STRING.value);

        // multiplatform default includes
        defaultIncludes.add("io.ktor.client.request.forms.InputProvider");

View on GitHub (pinned to fcec517be3)

Solutions

1. Add `-p useSpringBoot3=true` (Boot 3 baseline) or `-p useSpringBoot4=true` (Boot 4; also unlocks useJackson3).
2. Pick Boot 4 if you also want Jackson 3 — Boot 3 does not satisfy the Jackson 3 guard at KotlinClientCodegen.java:504.
3. Check the parsed value is the string 'true' — e.g. YAML `useSpringBoot3: yes` may serialize as something the guard rejects.

Example fix

# before
openapi-generator-cli generate -g kotlin --library=jvm-spring-restclient -i api.yaml
# after
openapi-generator-cli generate -g kotlin --library=jvm-spring-restclient -i api.yaml -p useSpringBoot4=true

# shell: spring-restclient needs an explicit boot baseline
if [ "$LIBRARY" = "jvm-spring-restclient" ]; then
  [ "$USE_SPRING_BOOT3" = "true" ] || [ "$USE_SPRING_BOOT4" = "true" ] || {
    echo "jvm-spring-restclient requires useSpringBoot3=true or useSpringBoot4=true" >&2; exit 2; }
fi

try {
    DefaultGenerator().opts(clientOptInput).generate()
} catch (e: RuntimeException) {
    throw IllegalStateException("jvm-spring-restclient missing Spring Boot baseline: ${e.message}", e)
}

When it happens

Trigger: `-g kotlin --library=jvm-spring-restclient` with neither boot flag; or both flags explicitly false; CI scripts that only pass --library and -i.

Common situations: Assuming the generator picks a default Boot version; shared generate scripts across generators where the boot flags were only added for the spring server generator.

Related errors

• useJackson3 with jvm-spring-restclient requires useSpringBoo
• {enumSerializationLibrary} is an invalid enum property namin
• useJackson3 requires serializationLibrary=jackson
• openApiNullable cannot be set with useJackson3
• useJackson3 is only supported for the jvm-okhttp4 and jvm-sp

AI-assisted analysis of OpenAPITools/openapi-generator@fcec517be3 (2026-08-22). Data as JSON: /api/errors/4e4bdd8f1511f982. Report an issue: GitHub.