vectordotdev/vector · error

global log_schema.message_key to be valid path

Error message

global log_schema.message_key to be valid path

What it means

`log_schema().message_key()` returns an Option; it is None when the global `log_schema.message_key` configuration is unset, blank, or does not parse into a valid value path. The kubernetes_logs transform utilities unconditionally `expect("global log_schema.message_key to be valid path")` when computing the message target path for the Legacy log namespace, so a schema without a usable message key panics while the pipeline is being built or run.

Source

Thrown at src/sources/kubernetes_logs/transform_utils/mod.rs:10

use vector_lib::config::{LogNamespace, log_schema};
use vrl::{owned_value_path, path::OwnedTargetPath};

pub(crate) fn get_message_path(log_namespace: LogNamespace) -> OwnedTargetPath {
    match log_namespace {
        LogNamespace::Vector => OwnedTargetPath::event(owned_value_path!()),
        LogNamespace::Legacy => OwnedTargetPath::event(
            log_schema()
                .message_key()
                .expect("global log_schema.message_key to be valid path")
                .clone(),
        ),
    }
}

View on GitHub (pinned to 3708c39b12)

Solutions

1. Set a valid `log_schema.message_key` (default `message`) at the top level of the config
2. Run `vector validate <config>` before deploying to catch schema mistakes
3. If embedding: propagate a configuration error instead of expect when the key is absent

Example fix

# before
log_schema:
  timestamp_key: ts
  # message_key missing or empty
# after
log_schema:
  message_key: message
  timestamp_key: ts

# shell: catch a missing/blank message_key before deploy
vector validate /etc/vector/vector.yaml --no-environment
# and confirm the key resolves
! grep -qE '^\s*message_key:\s*$' /etc/vector/vector.yaml

When it happens

Trigger: Running kubernetes_logs (or any Legacy-namespace component that goes through `get_message_path`) with a top-level `log_schema:` block whose `message_key` is omitted, empty, or an invalid path expression.

Common situations: Operators overriding `log_schema` keys in vector.yaml (e.g. renaming message to msg) and mistyping or blanking the value; YAML indentation that puts `message_key` under the wrong block so the global schema ends up without it.

Related errors

• valid message key
• valid host key
• valid metadata key
• registered log schema required
• all json-file keys should be matched

AI-assisted analysis of vectordotdev/vector@3708c39b12 (2026-08-20). Data as JSON: /api/errors/b7bc3f7703840713. Report an issue: GitHub.