neondatabase/neon · warning · ApiError

Cannot manage failpoints because neon was compiled without…

Error message

Cannot manage failpoints because neon was compiled without failpoints support

What it means

Returned as HTTP 400 BadRequest by failpoints_handler in neon's http-utils when the binary was compiled without failpoints support: fail::has_failpoints() is false because the failpoints crate was compiled with its no-op configuration. The /failpoints management endpoint exists in every build, but only builds with the failpoints cargo feature actually embed failpoint instrumentation, so test/chaos scripts hitting the endpoint on a production build get this error.

Solutions

1. Rebuild the target service with failpoints enabled, e.g. cargo build --features failpoints (or the neon-specific testing profile that turns it on)
2. Point the failpoint test at a binary that was compiled with the feature (CI's test builds always are)
3. If you cannot rebuild, remove the failpoint-configuration step from the scenario

Example fix

# before
cargo build -p neon_pageserver        # no failpoints feature
curl -X POST localhost:9898/failpoints ...   # 400: compiled without failpoints support

# after
cargo build -p neon_pageserver --features failpoints
curl -X POST localhost:9898/failpoints -d '[{"name":"persistence-after-s3-sync","actions":"return"}]'

# Skip failpoint setup on builds without support:
if curl -sf -X POST localhost:9898/failpoints -H 'Content-Type: application/json' \
     -d '[]' >/dev/null 2>&1; then
  apply_failpoints
else
  echo "failpoints not compiled in; rebuild with --features failpoints"
fi

# Treat 400 'compiled without failpoints support' as a skip, not a failure:
status=$(curl -s -o resp.txt -w '%{http_code}' -X POST localhost:9898/failpoints -d @fp.json)
if [ "$status" = 400 ] && grep -q 'without failpoints support' resp.txt; then
  exit 0  # capability missing; not a test failure
fi

When it happens

Trigger: POST /failpoints with a ConfigureFailpointsRequest body against a neon service binary compiled without --features failpoints; the handler rejects the request before parsing or applying any failpoint configuration.

Common situations: Running chaos/test scripts designed for CI builds against locally built or release binaries; forgetting to enable the failpoints feature in a custom build; CI image rebuilds that dropped the feature flag.

Related errors

• Failed to configure failpoints
• heap profiling not enabled
• duration must be 1-60 secs
• Failed to parse json request
• failed to parse

AI-assisted analysis of neondatabase/neon@8f60b04da4 (2026-08-16). Data as JSON: /api/errors/7e63cdbc2d91f934. Report an issue: GitHub.

Appendix: source

Thrown at libs/http-utils/src/failpoints.rs:28

/// Information for configuring a single fail point
#[derive(Debug, Serialize, Deserialize)]
pub struct FailpointConfig {
    /// Name of the fail point
    pub name: String,
    /// List of actions to take, using the format described in `fail::cfg`
    ///
    /// We also support `actions = "exit"` to cause the fail point to immediately exit.
    pub actions: String,
}

/// Configure failpoints through http.
pub async fn failpoints_handler(
    mut request: Request<Body>,
    _cancel: CancellationToken,
) -> Result<Response<Body>, ApiError> {
    if !fail::has_failpoints() {
        return Err(ApiError::BadRequest(anyhow::anyhow!(
            "Cannot manage failpoints because neon was compiled without failpoints support"
        )));
    }

    let failpoints: ConfigureFailpointsRequest = json_request(&mut request).await?;
    for fp in failpoints {
        tracing::info!("cfg failpoint: {} {}", fp.name, fp.actions);

        // We recognize one extra "action" that's not natively recognized
        // by the failpoints crate: exit, to immediately kill the process
        let cfg_result = apply_failpoint(&fp.name, &fp.actions);

        if let Err(err_msg) = cfg_result {
            return Err(ApiError::BadRequest(anyhow::anyhow!(
                "Failed to configure failpoints: {err_msg}"
            )));
        }
    }

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