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# NSURLErrorNetworkUnavailableReason

An enumeration of reasons why a task couldn’t satisfy networking constraints.

```
enum NSURLErrorNetworkUnavailableReason : NSInteger;
```

## Overview

The network may be unavailable due to restrictions placed on the [`URLSessionConfiguration`](/documentation/Foundation/URLSessionConfiguration), such as [`allowsConstrainedNetworkAccess`](/documentation/Foundation/URLSessionConfiguration/allowsConstrainedNetworkAccess), [`allowsExpensiveNetworkAccess`](/documentation/Foundation/URLSessionConfiguration/allowsExpensiveNetworkAccess) and [`allowsCellularAccess`](/documentation/Foundation/URLSessionConfiguration/allowsCellularAccess).

## Topics

### Unavailability reasons

[`NSURLErrorNetworkUnavailableReasonCellular`](/documentation/Foundation/NSURLErrorNetworkUnavailableReason/NSURLErrorNetworkUnavailableReasonCellular)

A reason that indicates network is unavailable because the interface is cellular and cellular network is disabled.

[`NSURLErrorNetworkUnavailableReasonConstrained`](/documentation/Foundation/NSURLErrorNetworkUnavailableReason/NSURLErrorNetworkUnavailableReasonConstrained)

A reason that indicates network is unavailable because the user enabled “Low Data Mode” in the Settings app.

[`NSURLErrorNetworkUnavailableReasonExpensive`](/documentation/Foundation/NSURLErrorNetworkUnavailableReason/NSURLErrorNetworkUnavailableReasonExpensive)

A reason that indicates network is unavailable because the system marked the interface as expensive.


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