---
url: https://masyaka.github.io/injecute/errors/nothing-to-replace.md
description: A registration replaces a key that nothing is registered under
---

# `INJECUTE_NOTHING_TO_REPLACE`

**A registration replaces a key that nothing is registered under.**

## How to fix it

replace: true replaces a registration of this container or a parent. Nothing has this key, which usually means a registration is missing: a module that was not applied, or a typo in the key. Register the original first, or remove replace: true if this is the first registration.

## Example

```ts
const app = new DIContainer().addSingleton('db', createDb);

app.fork({ isolated: true }).addInstance('dbb', fakeDb, { replace: true }); // throws: a typo
app.fork({ isolated: true }).addInstance('db', fakeDb, { replace: true }); // replaces "db"
```

## Why it throws

`replace: true` says that something is registered under the key. When nothing is, the replacement
would quietly become a new service that nothing uses, and the original you meant to replace would
still be in place. Common causes:

* a typo in the key;
* a module that should register the original wasn't applied, or is applied after the replacement:
  apply modules first, then replace;
* a test override for a service the app no longer has.

If this is the first registration of the key, remove `replace: true`.

## Handling it in code

```ts
import { InjecuteError } from 'injecute';

try {
  // ...
} catch (error) {
  if (error instanceof InjecuteError && error.code === 'INJECUTE_NOTHING_TO_REPLACE') {
    // error.message explains what happened; error.path is the resolution chain
  }
}
```

[All error codes](./index.md)