hasura/graphql-engine · error · Error

Error while building the request for the pre-parse plugin {0

Error message

Error while building the request for the pre-parse plugin {0} - {1}

What it means

The pre-response plugin could not build the HTTP request to its hook — invalid URL or rejected headers/body. As with 1285, the message text mentions 'pre-parse plugin' though it is raised by the pre-response executor; field {1} carries the builder's reason.

Source

Thrown at v3/crates/plugins/pre-response-plugin/src/execute/common.rs:19

use std::{collections::BTreeMap, str::FromStr};

use axum::{
    http::{HeaderMap, HeaderName, StatusCode},
    response::IntoResponse,
};

use hasura_authn_core::Session;
use lang_graphql::{ast::common as ast, http::RawRequest};
use open_dds::plugins::{LifecyclePluginUrl, LifecyclePreResponsePluginHookConfigRequest};
use reqwest::header::HeaderValue;
use serde::Serialize;
use tracing_util::{ErrorVisibility, TraceableError};

#[derive(Debug, thiserror::Error)]
pub enum Error {
    #[error("Error while making the HTTP request to the pre-parse plugin {0} - {1}")]
    ErrorWhileMakingHTTPRequestToTheHook(String, reqwest::Error),
    #[error("Error while building the request for the pre-parse plugin {0} - {1}")]
    BuildRequestError(String, String),
    #[error("Reqwest error: {0}")]
    ReqwestError(reqwest::Error),
    #[error("Error parsing the request: {0}")]
    PluginRequestParseError(serde_json::Error),
    #[error("Error parsing the engine response: {0}")]
    EngineResponseParseError(serde_json::Error),
    #[error("Unexpected status code: {0}")]
    UnexpectedStatusCode(u16),
    #[error("Error serializing the modified response: {0}")]
    ResponseSerializationError(serde_json::Error),
    #[error("Error while preparing the response: {0}")]
    ResponsePreparationError(axum::http::Error),
}

impl TraceableError for Error {
    fn visibility(&self) -> ErrorVisibility {
        ErrorVisibility::Internal

View on GitHub (pinned to 724551b9ae)

Solutions

1. Inspect the {1} field for the exact builder rejection reason.
2. Validate the URL with url::Url::parse at startup/config load.
3. Sanitize header names/values before they are applied to the request builder.

url::Url::parse(cfg.pre_response_hook_url.trim())?;

When it happens

Trigger: Malformed hook URL in pre-response plugin config, or header values containing illegal characters pulled from config or env vars.

Common situations: Config typo in the hook URL; template-rendered URLs producing invalid output; newline or non-ASCII characters in a header value sourced from env.

Related errors

• User error from plugin {plugin_name}
• Error while building the request for the pre-parse plugin {0
• Error while making the HTTP request to the pre-parse plugin
• Unexpected status code: {0}
• Error while building the request for the pre-parse plugin {0

AI-assisted analysis of hasura/graphql-engine@724551b9ae (2026-08-28). Data as JSON: /api/errors/806c34a6e07a86b2. Report an issue: GitHub.