zed-industries/zed · error

{} cannot be built from JSON

Error message

{} cannot be built from JSON

What it means

Generated by the derive_action macro: the action type was declared with no_json, so its from_json/to_json ActionPayload builders return this error. It fires at runtime when a caller tries to deserialize this action (e.g. replaying serialized keybindings), not at compile time.

Source

Thrown at crates/gpui_macros/src/derive_action.rs:123

    if name.contains("::") {
        panic!(
            "in #[action] attribute: `name = \"{name}\"` must not contain `::`, \
            also specify `namespace` instead"
        );
    }

    let full_name = if let Some(namespace) = namespace {
        format!("{namespace}::{name}")
    } else {
        name
    };

    let is_unit_struct = matches!(&input.data, Data::Struct(data) if data.fields.is_empty());

    let build_fn_body = if no_json {
        let error_msg = format!("{} cannot be built from JSON", full_name);
        quote! { Err(gpui::private::anyhow::anyhow!(#error_msg)) }
    } else if is_unit_struct {
        quote! { Ok(Box::new(Self)) }
    } else {
        quote! { Ok(Box::new(gpui::private::serde_json::from_value::<Self>(_value)?)) }
    };

    let json_schema_fn_body = if no_json || is_unit_struct {
        quote! { None }
    } else {
        quote! { Some(<Self as gpui::private::schemars::JsonSchema>::json_schema(_generator)) }
    };

    let deprecated_aliases_fn_body = if deprecated_aliases.is_empty() {
        quote! { &[] }
    } else {
        let aliases = deprecated_aliases.iter();
        quote! { &[#(#aliases),*] }
    };

View on GitHub (pinned to f4178619ac)

Solutions

1. Avoid serializing/deserializing this action type; keep it dispatch-only
2. If JSON round-tripping is needed, remove no_json and implement proper (de)serialization
3. Audit generic action-replay paths to skip actions whose type opted out of JSON

When it happens

Trigger: Thrown at crates/gpui_macros/src/derive_action.rs:123 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zed-industries/zed@f4178619ac (2026-08-20). Data as JSON: /api/errors/b503dce33ab9f8ee. Report an issue: GitHub.