quarkusio/quarkus · error · IllegalArgumentException

Code generation failed. Please check the log above for detai

Error message

Code generation failed. Please check the log above for details.

What it means

Quarkus gRPC protoc plugin validation: while generating Mutiny stubs, each service in the proto must have an explicit java_package option (or usable java package info). If any service's proto lacks it, validation sets failed=true and throws this IllegalArgumentException, instructing the developer to read the log lines printed just above the error for the offending proto file.

Source

Thrown at extensions/grpc/protoc/src/main/java/io/quarkus/grpc/protoc/plugin/MutinyGrpcGenerator.java:72

                .collect(Collectors.toList());

        List<ServiceContext> services = findServices(protosToGenerate, typeMap);
        validateServices(services);
        return generateFiles(services);
    }

    private void validateServices(List<ServiceContext> services) {
        boolean failed = false;
        for (ServiceContext service : services) {
            if (service.packageName == null || service.packageName.isBlank()) {
                log.log(Level.SEVERE, "Using the default java package is not supported for "
                        + "Quarkus gRPC code generation. Please specify `option java_package = \"your.package\"` in "
                        + service.protoName);
                failed = true;
            }
        }
        if (failed) {
            throw new IllegalArgumentException("Code generation failed. Please check the log above for details.");
        }
    }

    private List<ServiceContext> findServices(List<DescriptorProtos.FileDescriptorProto> protos, ProtoTypeMap typeMap) {
        List<ServiceContext> contexts = new ArrayList<>();

        protos.forEach(fileProto -> {
            for (int serviceNumber = 0; serviceNumber < fileProto.getServiceCount(); serviceNumber++) {
                ServiceContext serviceContext = buildServiceContext(
                        fileProto.getService(serviceNumber),
                        typeMap,
                        fileProto.getSourceCodeInfo().getLocationList(),
                        serviceNumber);
                serviceContext.protoName = fileProto.getName();
                serviceContext.packageName = extractPackageName(fileProto);
                contexts.add(serviceContext);
            }
        });

View on GitHub (pinned to e1c734241f)

Solutions

1. Add 'option java_package = "your.package.name";' to the offending .proto file (the file name is printed in the log above the error).
2. Alternatively set 'option java_multiple_files = true;' together with java_package if you want per-type classes.
3. Regenerate with mvn clean compile after editing the proto.
4. Check build log entries above the failure — each offending proto/service is listed there.

Example fix

// before
syntax = "proto3";
service Greeter { rpc SayHello (HelloRequest) returns (HelloReply); }
// after
syntax = "proto3";
option java_package = "com.example.grpc";
service Greeter { rpc SayHello (HelloRequest) returns (HelloReply); }

// check every proto before building
files.filter { it.endsWith(".proto") }.forEach { f ->
    val text = f.readText()
    require("option java_package" in text) { "${f.name}: missing option java_package" }
}

try {
    buildWithGrpcCodegen();
} catch (IllegalArgumentException e) {
    if (e.getMessage().contains("Code generation failed")) {
        // read log above for the proto file(s) lacking java_package and fix them
    } else throw e;
}

When it happens

Trigger: Running a Quarkus build with a .proto file that declares services but no 'option java_package = "your.package";' — the plugin's validateServices step fails before generating files.

Common situations: Copying protos from non-Java projects (no java_package option); migrating plain gRPC Java projects to Quarkus; hand-written minimal proto files.

Related errors

• The original implementation class of a gRPC service not foun
• Failed to list matching files in ${importPath}
• Failed to compile avro IDL file: ${filePath} to Java
• Failed to compile avro protocole file: ${filePath} to Java
• Unable to find the following conversion class: ${customConve

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/bd7d534ccc5782f7. Report an issue: GitHub.