jdx/mise · error

Failed to parse schema JSON: {}

Error message

Failed to parse schema JSON: {}

What it means

head_async_with_headers issues HTTP HEAD requests (commonly for checking artifact existence/size) and, like all network methods on this client, first ensures offline mode is disabled. If the `offline` setting is on, it throws "offline mode is enabled" without sending the request.

Source

Thrown at crates/mise-interactive-config/build.rs:63

    let repo_schema = manifest_dir
        .parent()
        .unwrap()
        .parent()
        .unwrap()
        .join("schema/mise.json");
    let schema_path = if local_schema.exists() {
        local_schema
    } else {
        repo_schema
    };

    println!("cargo:rerun-if-changed={}", schema_path.display());

    let schema_content = fs::read_to_string(&schema_path)
        .unwrap_or_else(|e| panic!("Failed to read schema at {}: {}", schema_path.display(), e));

    let schema: Value = serde_json::from_str(&schema_content)
        .unwrap_or_else(|e| panic!("Failed to parse schema JSON: {}", e));

    let defs = schema.get("$defs");

    // Extract top-level properties and classify them
    let mut sections = Vec::new();
    let mut entries = Vec::new(); // (name, description, type)

    if let Some(properties) = schema.get("properties").and_then(|p| p.as_object()) {
        for (name, prop) in properties {
            // Skip deprecated and internal properties
            if prop
                .get("deprecated")
                .and_then(|d| d.as_bool())
                .unwrap_or(false)
            {
                continue;
            }
            if name == "_" {

View on GitHub (pinned to afd2eddd3a)

Solutions

1. Turn off offline mode: `mise settings set offline false` or unset MISE_OFFLINE
2. Set `offline = false` in mise.toml [settings]
3. Skip install operations needing remote checks; use locally installed versions

Example fix

// before
# settings.toml
[settings]
offline = true

// after
[settings]
offline = false

mise settings get offline  # must print false before HEAD checks

match client.head_async_with_headers(url, &headers).await {
    Err(e) if e.to_string().contains("offline mode") => assume_artifact_absent_or_cached(),
    r => r?,
}

When it happens

Trigger: Calling head_async_with_headers while Settings::get().offline() is true — e.g. a backend probing a download URL during install with MISE_OFFLINE=1 exported.

Common situations: Tool installation flows that HEAD-check release assets running on a machine/env where offline mode was enabled to speed up or lock down mise.

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

• cannot encode #{value.class} as JSON
• Failed to read schema at {}: {}
• cli feature is not enabled
• should not be called for system tool
• Got HTML instead of text from {}

AI-assisted analysis of jdx/mise@afd2eddd3a (2026-09-09). Data as JSON: /api/errors/65f515de210c4471. Report an issue: GitHub.