clockworklabs/SpacetimeDB · error · anyhow::Error

Unknown server language

Error message

Unknown server language: {}

What it means

`spacetime init` parses the server language string via ServerLanguage::from_str. Accepted values after lowercasing: rust, csharp (alias c#), typescript, cpp (aliases c++, cxx). Any other string is rejected with 'Unknown server language: <s>'. The check is case-insensitive, but whitespace is not trimmed and spelling variants beyond the listed aliases fail.

Solutions

1. Use one of the accepted values: rust, csharp (or c#), typescript, cpp (or c++, cxx)
2. Trim and normalize the value in scripts before passing it (lowercase, strip spaces)
3. Check `spacetime init --help` for your CLI version's accepted list

Example fix

# before
spacetime init --lang "C++ "
# after
spacetime init --lang cpp

#!/usr/bin/env bash
SERVER_LANGS='rust|csharp|c#|typescript|cpp|c++|cxx'
lang="$(echo "$1" | tr '[:upper:]' '[:lower:]' | xargs)"
[[ "$lang" =~ ^($SERVER_LANGS)$ ]] || { echo "server lang must be: $SERVER_LANGS" >&2; exit 2; }
spacetime init --lang "$lang"

When it happens

Trigger: Passing `spacetime init --lang <s>` (server language flag) with an unsupported value such as 'go', 'python', 'C #', 'cplus', or a value with leading/trailing whitespace. Also triggered by automation piping a language name from another tool's output verbatim.

Common situations: Assuming a language exists because the client SDK does (e.g. 'unity' or 'python' is not a server language); shell scripts echoing 'C++' with odd quoting/whitespace; documentation drift between CLI versions where accepted sets changed.

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 client 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/2e190be2beb40fb0. Report an issue: GitHub.

Appendix: source

Thrown at crates/cli/src/subcommands/init.rs:80

}

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

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

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ClientLanguage {
    Rust,
    Csharp,
    TypeScript,
}

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

View on GitHub (pinned to fdd647dfac)