vectordotdev/vector · error

source output misconfigured - output for port

Error message

source output misconfigured - output for port {:?} missing

What it means

During topology schema computation, possible_definitions unwraps a source's output for a given port that source_output_for_port already reported as existing (Ok(Some(_))), so the None branch is marked unreachable. Hitting it means source_output_for_port and its output lookup disagree — the source claimed to have an output for the port but returned None. This indicates a source implementation bug or an inconsistent build unit graph.

Solutions

1. Inspect the source implementation's output_for_port to ensure it cannot return Ok(None) for a port it advertises
2. Rebuild with consistent crate versions to rule out a stale build
3. File/check a Vector bug with the topology config that triggers it

// Validate the topology before schema expansion
vector validate --no-environment config.yaml

When it happens

Trigger: A source component whose output implementation returns Ok(None) for a port it earlier reported as existing; adding a custom source with a misimplemented output_for_port; race/regression in topology builder against source unit metadata.

Common situations: Developing a custom Vector source with named output ports; Vector version mismatches between library crates where the topology and source code disagree.

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

• source output misconfigured
• transform must exist - already found inputs
• transform output misconfigured - output for port
• already found inputs
• can't run runner twice

AI-assisted analysis of vectordotdev/vector@bdb87aeaa4 (2026-09-16). Data as JSON: /api/errors/d8e8826c4ba17cc9. Report an issue: GitHub.

Appendix: source

Thrown at src/topology/schema.rs:46

        return Ok(vec![]);
    }

    // Try to get the definition from the cache.
    if let Some(definition) = cache.get(&(config.schema_enabled(), inputs.to_vec())) {
        return Ok(definition.clone());
    }

    let mut definitions = Vec::new();

    for input in inputs {
        let key = &input.component;

        // If the input is a source, the output is merged into the top-level schema.
        if let Ok(maybe_output) = config.source_output_for_port(key, &input.port) {
            let mut source_definition = input.with_definitions(
                maybe_output
                    .unwrap_or_else(|| {
                        unreachable!(
                            "source output misconfigured - output for port {:?} missing",
                            &input.port
                        )
                    })
                    .schema_definition(config.schema_enabled()),
            );

            if contains_never(&source_definition) {
                return Err(Error::ContainsNever);
            }

            definitions.append(&mut source_definition);
        }

        // If the input is a transform, the output is merged into the top-level schema
        if let Some(inputs) = config.transform_inputs(key) {
            let input_definitions =
                possible_definitions(inputs, config, enrichment_tables.clone(), cache)?;

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