# rpc error: code = InvalidArgument desc = missing required field: user_id

- **ID:** `go/grpc-missing-required-field`
- **Domain:** go
- **Category:** data_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

The request message does not include a field marked as required in the proto definition (though proto3 doesn't have required, custom validation may enforce it).

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 1.9 | active | — | — |

## Workarounds

1. **** (100% success)
   ```
   req.UserId = "12345"
   ```
2. **** (80% success)
   ```
   Use optional keyword in proto3 to generate pointer fields.
   ```

## Dead Ends

- **** — Zero value may still be considered missing by validation logic. (70% fail)
- **** — The server expects a specific field name. (90% fail)