clockworklabs/SpacetimeDB · error · anyhow::Error

Unknown client language

Error message

Unknown client language: {}

What it means

Client-language counterpart of the server-language parser in `spacetime init`. ClientLanguage::from_str accepts only rust, csharp (alias c#), and typescript — note there is NO cpp/client option, and values like 'unrealcpp', 'javascript', or 'ts' are rejected with 'Unknown client language: <s>'.

Solutions

1. Use exactly rust, csharp (or c#), or typescript
2. If you need Unreal C++ client bindings, init with a supported client language (or none) and run `spacetime generate --lang unrealcpp` separately
3. Normalize values in automation: lowercase, expand 'ts'→'typescript'

Example fix

# before
spacetime init --client-lang ts
# after
spacetime init --client-lang typescript

#!/usr/bin/env bash
CLIENT_LANGS='rust|csharp|c#|typescript'
lang="$(echo "$1" | tr '[:upper:]' '[:lower:]' | xargs)"
[[ "$lang" =~ ^($CLIENT_LANGS)$ ]] || { echo "client lang must be: $CLIENT_LANGS (no ts/javascript/unrealcpp)" >&2; exit 2; }
spacetime init --client-lang "$lang"

When it happens

Trigger: Passing `spacetime init --client-lang <s>` with a value outside {rust, csharp, c#, typescript}. Common misses: 'ts' (not an alias), 'javascript' (not an alias), 'unrealcpp' (not a client language for init templates).

Common situations: Mapping 'typescript'→'ts' out of habit; Unity/Unreal developers trying 'unrealcpp' as a client language; scripts sharing one language variable between server and client flags where the server accepts cpp but the client parser does not.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• Unknown server language
• Either --out-dir or --uproject-dir is required
• --namespace is only supported with --lang csharp
• --unreal-module-name is required for --lang unrealcpp
• --uproject-dir is required for --lang unrealcpp

AI-assisted analysis of clockworklabs/SpacetimeDB@fdd647dfac (2026-08-20). Data as JSON: /api/errors/71e8cfab8d3e873e. Report an issue: GitHub.

Appendix: source

Thrown at crates/cli/src/subcommands/init.rs:106

    Csharp,
    TypeScript,
}

impl ClientLanguage {
    fn as_str(&self) -> &'static str {
        match self {
            ClientLanguage::Rust => "rust",
            ClientLanguage::Csharp => "csharp",
            ClientLanguage::TypeScript => "typescript",
        }
    }

    fn from_str(s: &str) -> anyhow::Result<Option<Self>> {
        match s.to_lowercase().as_str() {
            "rust" => Ok(Some(ClientLanguage::Rust)),
            "csharp" | "c#" => Ok(Some(ClientLanguage::Csharp)),
            "typescript" => Ok(Some(ClientLanguage::TypeScript)),
            _ => Err(anyhow!("Unknown client language: {}", s)),
        }
    }
}

pub struct TemplateConfig {
    pub project_name: String,
    pub project_path: PathBuf,
    pub template_type: TemplateType,
    pub server_lang: Option<ServerLanguage>,
    pub client_lang: Option<ClientLanguage>,
    pub github_repo: Option<String>,
    pub template_def: Option<TemplateDefinition>,
    pub use_local: bool,
    pub native_aot: bool,
}

#[derive(Debug, Clone, Default)]
pub struct InitOptions {

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