---
applies_to: ["server"]
authors: ["drganjoo"]
references: ["smithy-rs#3813"]
breaking: true
new_feature: false
bug_fix: true
---
Operations with event stream member shapes must include `ValidationException` in the errors list. This is necessary because the member shape is a required field, and the builder for the operation input or output returns a `std::result::Result` with the error set to `crate::model::ValidationExceptionField`.
