[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Fs](https://evolu.dev/docs/api-reference/common/Fs) › FsErrorReason

```ts
type FsErrorReason =
  | "NotFound"
  | "AlreadyExists"
  | "PermissionDenied"
  | "IsDirectory"
  | "NotDirectory"
  | "NotEmpty"
  | "Busy"
  | "Unknown";
```

Defined in: [packages/common/src/Fs.ts:421](https://github.com/evoluhq/evolu/blob/ecbac001e0c18bbc45b44715f49ecc3a768c5ec9/packages/common/src/Fs.ts#L421)

Why a file system operation failed, mapped from the platform's error code.