# rustup: error: toolchain 'nightly-x86_64-unknown-linux-gnu' is not installed / error: no override and no default toolchain set

**Code:** `error: toolchain 'stable' is not installed / override toolchain not found` · **Category:** Rust · **Seen on:** Rust

rustup can't find the toolchain requested by `rust-toolchain.toml`, an override, or no default is set.

## Meaning

Install it: `rustup toolchain install stable` (or the one named), set a default with `rustup default stable`, or remove/correct `rust-toolchain(.toml)`. In CI install the toolchain before building. Add targets/components: `rustup target add wasm32-unknown-unknown`, `rustup component add clippy rustfmt`.

## Common causes

- Fresh machine/CI without a default toolchain
- `rust-toolchain.toml` names an uninstalled channel/date
- Removed toolchain
- Missing target/component
- Corrupted rustup install

## Quick fix

1. `rustup default stable`
2. `rustup toolchain install nightly-2025-01-01` for pinned files
3. `rustup component add clippy rustfmt` / `rustup target add TARGET`

## Detailed fix by platform

### Linux

1. `rustup show && rustup toolchain list`

## How to diagnose

1. **Toolchain** — Installed?
2. **File** — rust-toolchain.toml?
3. **Component** — Present?

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Source: [WhatIsMyError](https://whatismyerror.com/errors/rust/rustup-toolchain-not-installed)