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# URLError.NetworkUnavailableReason.constrained

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

```
case constrained
```

## Discussion

This reason occurs when the following conditions are true:

- The only available network is cellular.
- The user has enabled “Low Data Mode” option in the Cellular Data Options section of the Settings app.
- The [`URLSessionConfiguration`](/documentation/Foundation/URLSessionConfiguration) property [`allowsConstrainedNetworkAccess`](/documentation/Foundation/URLSessionConfiguration/allowsConstrainedNetworkAccess) is <doc://com.apple.documentation/documentation/Swift/false>.

---

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