signalapp/Signal-Server · error · FieldValidationException

message expected to be present

Error message

message expected to be present

What it means

PresentFieldValidator.validateMessageValue throws FieldValidationException when a proto message field annotated as required-present is null. Signal's gRPC layer uses this to reject requests missing an embedded message sub-field.

Solutions

1. Set the required message field via its setter (e.g. .setServiceIdentifier(...)) before building the request
2. Client-side null-check nested messages before sending
3. Compare against the proto definition to enumerate which message fields are annotated as required

Example fix

// before
Request.newBuilder().build(); // nested message never set
// after
Request.newBuilder()
    .setServiceIdentifier(ServiceId.newBuilder().setAci(aciUuid).build())
    .build();

if (request.getServiceIdentifier() == null) throw new IllegalArgumentException("service identifier message is required");

boolean hasMessage(Request r) { return r.hasServiceIdentifier(); }

try { stub.call(request); } catch (StatusRuntimeException e) { if (e.getStatus().getCode() == Status.Code.INVALID_ARGUMENT) { /* handle missing message field */ } }

When it happens

Trigger: Calling a Signal gRPC endpoint without setting a required nested message field (e.g. missing ServiceIdentifier, missing DeviceSpecifier), so the validator receives a null Message.

Common situations: Clients forgetting to set a nested message builder; proto3 code assuming unset message fields default to an instance rather than null; copy-pasted request builders missing one sub-message.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• string expected to be non-empty
• repeated field is expected to be non-empty
• INVALID_ARGUMENT
• value is not valid base64 url
• value is not in E164 format

AI-assisted analysis of signalapp/Signal-Server@100ab61c82 (2026-09-09). Data as JSON: /api/errors/da1077b98089a808. Report an issue: GitHub.

Appendix: source

Thrown at service/src/main/java/org/whispersystems/textsecuregcm/grpc/validators/PresentFieldValidator.java:29

public class PresentFieldValidator extends FieldValidator<Boolean> {

  public PresentFieldValidator() {
    super("present",
        Set.of(Descriptors.FieldDescriptor.Type.MESSAGE),
        MissingOptionalAction.FAIL,
        true);
  }

  @Override
  protected Boolean resolveExtensionValue(final Object extensionValue) throws FieldValidationException {
    return requireFlagExtension(extensionValue);
  }

  @Override
  protected void validateMessageValue(final Boolean extensionValue, final Message msg) throws FieldValidationException {
    if (msg == null) {
      throw new FieldValidationException("message expected to be present");
    }
  }
}

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