hasura/graphql-engine · error · Error

unable to parse introspection query: {0}

Error message

unable to parse introspection query: {0}

What it means

The internally-generated introspection query failed to parse with the GraphQL parser. This is an engine-side error: the fixed introspection query text could not be parsed, which normally signals a parser regression or corrupted build rather than user input.

Source

Thrown at v3/crates/graphql/lang-graphql/src/generate_graphql_schema.rs:13

/*
This module provides functions to generate introspection result as GraphQL schema
for each namespace from the schema.
 */
use json_ext;
use std::collections::BTreeMap;
use std::sync::OnceLock;
use tracing_util::SpanVisibility;
use tracing_util::{ErrorVisibility, TraceableError};

#[derive(Debug, thiserror::Error)]
pub enum Error {
    #[error("unable to parse introspection query: {0}")]
    ParseIntrospectionQuery(String),
    #[error("unable to normalize introspection query: {0}")]
    NormalizeIntrospectionQuery(String),
    #[error("unable to find field call")]
    FieldCallNotFound,
    #[error("Only __schema field is expected but found: {name:}")]
    OnlySchemaFieldExpected { name: String },
    #[error("introspection query failed: {0}")]
    IntrospactionQueryError(#[from] crate::introspection::Error),
    #[error("unable to serialize to json: {0}")]
    SerializeJson(#[from] serde_json::Error),
}
impl TraceableError for Error {
    fn visibility(&self) -> ErrorVisibility {
        ErrorVisibility::User
    }
}

View on GitHub (pinned to 724551b9ae)

Solutions

1. Upgrade the engine/lang-graphql crates to consistent versions
2. If you maintain a fork, diff the introspection query template against the parser's grammar
3. Report the issue with the parse error string if using stock releases

// Internal error: retry once; if persistent, upgrade/report

When it happens

Trigger: Executing an introspection request (e.g. GraphiQL/IDE loading the schema) where the hardcoded introspection query fails to lex/parse; parser and query-template version mismatch inside the engine.

Common situations: Mixing crate versions after a partial upgrade; a bug in a custom fork of the parser; essentially never caused by end-user queries.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• unable to normalize introspection query: {0}
• unable to find field call
• unable to fetch introspection schema: %w
• error in fetching introspection schema: %w
• %s: %d %s

AI-assisted analysis of hasura/graphql-engine@724551b9ae (2026-08-28). Data as JSON: /api/errors/e1bd321f6b42657a. Report an issue: GitHub.