flxzt/rnote · error · anyhow::Error

value is not a JSON object.

Error message

value is not a JSON object.

What it means

Thrown in TryFrom::<RnoteFileMaj0Min13>::try_from during the maj0min13->maj0min15 migration. After fetching the component's 'value', the code must treat it as a JSON object to look up stroke kinds like 'shapestroke'; if 'value' is a non-object (string, number, array, bool), migration fails. A null 'value' is tolerated and skipped, so this only fires for non-null non-objects.

Solutions

  1. Re-save the file with the original Rnote version so 'value' is serialized as a proper object.
  2. Inspect and repair the JSON: make each non-null component 'value' a JSON object with a kind key (shapestroke/textstroke/vectorimage/bitmapimage).
  3. Restore the file from backup/autosave instead of hand-editing.
  4. If the value is unfixable junk, replace it with null — null components are skipped by the migration.

Example fix

// before
{"value": "shapestroke-data"}
// after
{"value": {"shapestroke": {"shape": {"rect": {"transform": {...}}}}}}
Defensive patterns

Strategy: validation

Validate before calling

fn value_is_object_or_null(comp: &serde_json::Value) -> bool {
    comp.get("value").map_or(false, |v| v.is_object() || v.is_null())
}

Type guard

fn as_value_object<'a>(comp: &'a serde_json::Value) -> Option<&'a serde_json::Map<String, serde_json::Value>> {
    comp.get("value").and_then(|v| v.as_object())
}

Try / catch

match RnoteFileMaj0Min15::try_from(file) {
    Ok(f) => open(f),
    Err(e) if e.to_string().contains("value is not a JSON object") => {
        log::error!("stroke component value has wrong type: {e}");
        fallback_to_read_only_or_backup();
    }
    Err(e) => return Err(e),
}

Prevention

When it happens

Trigger: try_from encounters a stroke component whose 'value' is present and non-null but is not a JSON object, e.g. value: "stroke" or value: [1,2].

Common situations: Corrupted or externally edited .rnote files, or files written by a tool that serialized the component value as a scalar/array instead of an object.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

AI-assisted analysis of flxzt/rnote@bbc5354502 (2026-09-08). Data as JSON: /api/errors/b2703f983647a5b0. Report an issue: GitHub.

Appendix: source

Thrown at crates/rnote-engine/src/fileformats/rnoteformat/maj0min15.rs:42

            .get_mut("stroke_components")
            .ok_or(anyhow!(
                "engine snapshot does not contain 'stroke_components'."
            ))?
            .as_array_mut()
            .ok_or(anyhow!("stroke components is not a JSON array."))?
            .iter_mut()
        {
            let value = comp
                .as_object_mut()
                .ok_or(anyhow!("stroke component is not a JSON object."))?
                .get_mut("value")
                .ok_or(anyhow!("stroke component does not contain 'value'."))?;
            if value.is_null() {
                continue;
            }
            if let Some(shapestroke) = value
                .as_object_mut()
                .ok_or(anyhow!("value is not a JSON object."))?
                .get_mut("shapestroke")
            {
                let shape = shapestroke
                    .as_object_mut()
                    .ok_or(anyhow!("shapestroke is not a JSON object."))?
                    .get_mut("shape")
                    .ok_or(anyhow!("shapestroke does not contain 'shape'."))?;

                if let Some(rect) = shape
                    .as_object_mut()
                    .ok_or(anyhow!("shape is not a JSON object."))?
                    .get_mut("rect")
                {
                    convert_transform_to_affine_in_obj(rect)?;
                } else if let Some(ellipse) = shape
                    .as_object_mut()
                    .ok_or(anyhow!("shape is not a JSON object."))?
                    .get_mut("ellipse")

View on GitHub (pinned to bbc5354502)