wasmerio/wasmer · error · anyhow::Error

The `{compiler}` compiler is not included in this binary.

Error message

The `{compiler}` compiler is not included in this binary.

What it means

Wasmer binaries are built with a subset of compilers via cargo features. When get_sys_compiler_config matches a BackendType whose compiler was not compiled into this binary (cfg(not(all(singlepass, cranelift, llvm)))) it bails with the compiler name. This is a compile-feature availability error, not a code bug.

Source

Thrown at lib/cli/src/backend.rs:538

                    config.enable_verifier();
                }
                if self.enable_nan_canonicalization {
                    config.canonicalize_nans(true);
                }
                if let Some(p) = &self.profiler {
                    match p {
                        Profiler::Perfmap => config.enable_perfmap(),
                        Profiler::Gdb => config.enable_debugger(Debugger::Gdb),
                        Profiler::Lldb => config.enable_debugger(Debugger::Lldb),
                    }
                }

                Box::new(config)
            }
            BackendType::V8 => unreachable!(),
            #[cfg(not(all(feature = "singlepass", feature = "cranelift", feature = "llvm")))]
            compiler => {
                bail!("The `{compiler}` compiler is not included in this binary.")
            }
        };

        #[allow(unreachable_code)]
        {
            let mut compiler_config = compiler_config;
            if self.experimental_artifact {
                compiler_config.experimental_artifact(true);
            }
            Ok(compiler_config)
        }
    }
}

/// The compiler used for the store
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
#[allow(clippy::upper_case_acronyms, dead_code)]
pub enum BackendType {

View on GitHub (pinned to 8c4b9ee9d3)

Solutions

1. Install/rebuild Wasmer with the needed compiler feature (e.g. --features llvm)
2. Choose a backend that is included in this binary (e.g. --cranelift on a cranelift-only build)
3. Check available compilers with `wasmer compile --help` / binary feature info before scripting

Example fix

// before
cargo install wasmer --no-default-features --features cranelift
wasmer run app.wasm --llvm
// after
cargo install wasmer --features cranelift,llvm
wasmer run app.wasm --llvm

// probe feature availability before selecting a backend
#[cfg(not(feature = "llvm"))]
compile_error!("this build lacks the llvm compiler; rebuild with --features llvm");

fn backend_available(rt: &BackendType) -> bool {
    match rt {
        #[cfg(feature = "singlepass")]
        BackendType::Singlepass => true,
        #[cfg(feature = "cranelift")]
        BackendType::Cranelift => true,
        #[cfg(feature = "llvm")]
        BackendType::LLVM => true,
        _ => false,
    }
}

match result {
    Err(e) if e.to_string().contains("is not included in this binary") => {
        eprintln!("{}", e); // user must reinstall with the right features
        Err(e)
    }
    other => other?,
}

When it happens

Trigger: Selecting e.g. BackendType::LLVM (via --llvm) on a binary built without the `llvm` feature; any backend arm other than V8 when not all three compiler features are enabled.

Common situations: Minimal `wasmer` builds with only cranelift; distro-packaged binaries with trimmed features; switching backend flags in scripts without checking the installed binary's features.

Related errors

• The {} backend does not support the required features for th
• No backends support the required features for the Wasm modul
• The headless engine can't be chosen
• Unable to determine the wasmer dir: {e}
• The gdb profiler requires --experimental-artifact

AI-assisted analysis of wasmerio/wasmer@8c4b9ee9d3 (2026-09-01). Data as JSON: /api/errors/460105ed4d180189. Report an issue: GitHub.