---
title: BackendCreationError
summary: Errors that can arise from attempting to create a dynamic backend.
url: https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/backend/enum.BackendCreationError/
---

**Kind:** Enum  
**Module:** [backend](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/backend/)  
**Package:** fastly 0.13.1  
**Source:** https://docs.rs/crate/fastly/0.13.1/source/src/backend/builder.rs#54

```rust
pub enum BackendCreationError {
    ConnectTimeoutTooLarge(Duration),
    FirstByteTimeoutTooLarge(Duration),
    BetweenBytesTimeoutTooLarge(Duration),
    Disallowed,
    HostError(FastlyStatus),
    EncodingError(FromUtf8Error),
    NameTooLong(String),
    NameInUse,
    InvalidHealthcheckValue(String),
}
```

Errors that can arise from attempting to create a dynamic backend.

Perhaps the most critical of these is `Disallowed`, which will occur
if your service is not permitted to use dynamic backends.

## Variants

### ConnectTimeoutTooLarge

- `0`: `std::time::Duration`

Timeouts for backends must be less than 2^32 milliseconds, or
about a month and a half.

### FirstByteTimeoutTooLarge

- `0`: `std::time::Duration`

Timeouts for backends must be less than 2^32 milliseconds, or
about a month and a half.

### BetweenBytesTimeoutTooLarge

- `0`: `std::time::Duration`

Timeouts for backends must be less than 2^32 milliseconds, or
about a month and a half.

### Disallowed

This service is not allowed to create dynamic backends.

If you'd like to use dynamic backends, please contact your Fastly sales agent.

### HostError

- `0`: `fastly_shared::FastlyStatus`

Something internal went wrong with the service at runtime; you
may be able to do something to react to this information.

This value is identical to the values underlying `FastlyStatus`.

### EncodingError

- `0`: `std::string::FromUtf8Error`

There was a problem converting the new name from the host into
something we could turn into a Rust `String`.

Please check the prefix you provided, if you provided one, and make sure it's reasonable.

### NameTooLong

- `0`: `String`

The backend name provided was too long; please keep it to <255
characters.

### NameInUse

The backend name is already in use.

### InvalidHealthcheckValue

- `0`: `String`

A healthcheck value has an invalid size/format.

## Trait implementations

### impl Clone for BackendCreationError

#### clone

**Source:** https://docs.rs/crate/fastly/0.13.1/source/src/backend/builder.rs#53

```rust
fn clone(&self) -> Self
```

**Parameters**

- `self`: `&Self`

**Returns**

`Self`

### impl Debug for BackendCreationError

#### fmt

**Source:** https://docs.rs/crate/fastly/0.13.1/source/src/backend/builder.rs#53

```rust
fn fmt(&self, f: &mut Formatter<'_>) -> Result
```

**Parameters**

- `self`: `&Self`
- `f`: `&mut $crate::fmt::Formatter`

**Returns**

`$crate::fmt::Result`

### impl Display for BackendCreationError

#### fmt

**Source:** https://docs.rs/crate/fastly/0.13.1/source/src/backend/builder.rs#53

```rust
fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result
```

**Parameters**

- `self`: `&Self`
- `__formatter`: `&mut ::core::fmt::Formatter`

**Returns**

`::core::fmt::Result`

### impl Error for BackendCreationError

#### source

**Source:** https://docs.rs/crate/fastly/0.13.1/source/src/backend/builder.rs#53

```rust
fn source(&self) -> Option<&(dyn Error + 'static)>
```

**Parameters**

- `self`: `&Self`

**Returns**

`::core::option::Option<&(dyn Error + 'static)>`

### impl From<FastlyStatus> for BackendCreationError

#### from

**Source:** https://docs.rs/crate/fastly/0.13.1/source/src/backend/builder.rs#97

```rust
fn from(x: FastlyStatus) -> Self
```

**Parameters**

- `x`: `FastlyStatus`

**Returns**

`Self`

### impl From<FromUtf8Error> for BackendCreationError

#### from

**Source:** https://docs.rs/crate/fastly/0.13.1/source/src/backend/builder.rs#53

```rust
fn from(source: FromUtf8Error) -> Self
```

**Parameters**

- `source`: `std::string::FromUtf8Error`

**Returns**

`Self`

### impl PartialEq for BackendCreationError

#### eq

**Source:** https://docs.rs/crate/fastly/0.13.1/source/src/backend/builder.rs#53

```rust
fn eq(&self, other: &Self) -> bool
```

**Parameters**

- `self`: `&Self`
- `other`: `&Self`

**Returns**

`bool`

## Auto trait implementations

- `Freeze`
- `RefUnwindSafe`
- `Send`
- `Sync`
- `Unpin`
- `UnsafeUnpin`
- `UnwindSafe`

## Blanket implementations

- `Any`
- `Borrow<T>`
- `BorrowMut<T>`
- `CloneToUninit`
- `Downcast`
- `DowncastSync`
- `ErasedDestructor`
- `From<T>`
- `Into<U>`
- `IntoEither`
- `Same`
- `ToOwned`
- `ToString`
- `TryFrom<U>`
- `TryInto<U>`