dbt-labs/dbt-core · error

Error always present on ShouldBe::ButIsnt variant

Error message

Error always present on ShouldBe::ButIsnt variant

What it means

A panic from `.expect()` in `try_new` immediately after the message rewrite: the code takes ownership of the error (`take_err()`) stored on a `ShouldBe::ButIsnt` variant and asserts it is always present. This error is then converted into a richer `Invalid <type> definition` fs error. The panic signals the same ShouldBe invariant was broken at the error-value level.

Solutions

1. Fix the producer so ButIsnt always carries an Err value
2. Reproduce with the offending YAML key to identify which deserializer drops the error
3. Upgrade/pin dbt-jinja-utils to a fixed version
4. Replace the expect with a graceful fallback error to keep config parsing failing with a report instead of panicking

Example fix

// before
let err = variant.take_err().expect("Error always present on ShouldBe::ButIsnt variant");

// after
let err = variant.take_err()
    .unwrap_or_else(|| DbtError::new(ErrorCode::InvalidConfigError, "invalid value"));

let err = variant.take_err().unwrap_or_else(|| {
    DbtError::new(ErrorCode::InvalidConfigError, "invalid value")
});

When it happens

Trigger: Same path as the sibling expect: YAML config key deserialization produces `ShouldBe::ButIsnt` whose `take_err()` returns None while building the 'Invalid <S::type_name> definition' error.

Common situations: Only observed when internal serde plumbing constructs ButIsnt without carrying an error; typically after refactors of dbt_jinja_utils::serde or custom deserializers feeding project config parsing.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• Error message always present on ShouldBe::ButIsnt variant
• ModelPropertiesEntry guaranteed to exist for model
• Should be able to serialize job labels
• yaml deserializes into config type
• Adapter must be configured for the parse phase

AI-assisted analysis of dbt-labs/dbt-core@0267ce9170 (2026-09-07). Data as JSON: /api/errors/3210aec479d856af. Report an issue: GitHub.

Appendix: source

Thrown at crates/dbt-parser/src/dbt_project_config.rs:117

                    // An unknown key produces the error message `expected struct <SelfType>` due to
                    // the recursive type. Catch the error here to inject a more descriptive error.
                    let err_msg = variant
                        .as_err_msg()
                        .expect("Error message always present on ShouldBe::ButIsnt variant");
                    let self_type = std::any::type_name::<S>()
                        .rsplit("::")
                        .next()
                        .unwrap_or_default();
                    let detail = if err_msg.contains(&format!("expected struct {self_type}")) {
                        format!("Unrecognized key `{key_path}`. Custom keys must go under `+meta`.")
                    } else {
                        err_msg.to_string()
                    };

                    let err = variant
                        .take_err()
                        .expect("Error always present on ShouldBe::ButIsnt variant");
                    let fs_err = yaml_to_fs_error(err, filename).with_context(format!(
                        "Invalid {} definition `{}`: {}",
                        S::type_name(),
                        key_path,
                        detail
                    ));
                    emit_strict_parse_error(fs_err, dependency_package_name);
                }
            }
        };
        if !disallow_plus_prefix {
            warn_plus_prefixed_resource_paths::<S>("", configs, "", false);
        }
        Ok(recur_build_dbt_project_config(
            dbt_config,
            configs,
            "",
            &on_error,

View on GitHub (pinned to 0267ce9170)