What causes "Reqwest error: {0}" in hasura/graphql-engine?

Inspect the wrapped reqwest error for the failure category.

hasura/graphql-engine · error · Error

Reqwest error: {0}

Error message

Reqwest error: {0}

What it means

Generic reqwest::Error wrapper in the pre-route plugin executor for transport-level failures not covered by the explicit build/send variants (e.g. body read or decode errors during the hook call).

Source

Thrown at v3/crates/plugins/pre-route-plugin/src/execute.rs:26

use regex::Regex;
use serde::Serialize;

use open_dds::plugins::{
    LifecyclePreRoutePluginHook, LifecyclePreRoutePluginHookConfigRequestMethod,
    LifecyclePreRoutePluginHookIncomingHTTPMethod,
};
use serde_json::json;
use tracing_util::{
    ErrorVisibility, SpanVisibility, Traceable, TraceableError, set_attribute_on_active_span,
};

#[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("Unexpected status code: {0}")]
    UnexpectedStatusCode(u16),
    #[error("Error parsing the request: {0}")]
    PluginRequestParseError(serde_json::error::Error),
    #[error("HTTP method {0} not supported")]
    UnsupportedHTTPMethod(String),
    #[error("Invalid header name {0}")]
    InvalidHeaderName(String),
    #[error("Invalid header value {0}")]
    InvalidHeaderValue(String),
    #[error("Not found")]
    NotFound,
    // Only used in the pre-route plugin handler function. Defined to ensure consistent
    // response formatting in IntoResponse impl.
    #[error("Cannot load pre-route plugins: {0}")]
    CannotLoadPlugins(String),
}

View on GitHub (pinned to 724551b9ae)

Solutions

Inspect the wrapped reqwest error for the failure category.
Correlate with hook service logs for crashes/timeouts.
Disable problematic content-encodings on the hook or fix its gzip handling.

Defensive patterns

Strategy: retry

Try / catch

Err(Error::ReqwestError(ref e)) if e.is_timeout() || e.is_decode() => retry_with_jitter().await

Prevention

Set explicit timeouts; handle gzip correctly on the hook.
Watch for LB connection cuts between engine and hook.
Add circuit-breaking around the hook call.

When it happens

Trigger: The hook response stream fails mid-read, or another reqwest operation in the pre-route execution path errors.

Common situations: Hook crashes mid-response; LB cutting connections; decompression errors on gzip-encoded hook responses.

Understand the failure class

Background: 'Something went wrong' / 'Request failed (500)' / 'HTTP error! status: 404' — what failed HTTP requests actually mean and how to find the real cause — this error's family across 28 libraries.

Related errors

AI-assisted analysis of hasura/graphql-engine@724551b9ae (2026-08-28). Data as JSON: /api/errors/11d74c3576d6c115. Report an issue: GitHub.