---
title: Evaluation reasons and error codes
description: When you evaluate a flag using the binding's *Details methods or the OpenFeature SDK, the response includes a reason field that explains why a particular value was returned. If an error occurs, the response includes an errorCode field.
image: https://developers.cloudflare.com/dev-products-preview.png
---

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# Evaluation reasons and error codes

When you evaluate a flag using the binding's `*Details` methods or the OpenFeature SDK, the response includes a `reason` field that explains why a particular value was returned. If an error occurs, the response includes an `errorCode` field.

## Evaluation reasons

| Reason           | Description                                                                                                                        |
| ---------------- | ---------------------------------------------------------------------------------------------------------------------------------- |
| TARGETING\_MATCH | A targeting rule's conditions matched the evaluation context, and the rule's variation was returned.                               |
| SPLIT            | A targeting rule with a percentage rollout matched. The user fell within the rollout percentage and received the rule's variation. |
| DEFAULT          | No targeting rule matched the evaluation context. The flag's default variation was returned.                                       |
| DISABLED         | The flag is disabled. The default variation was returned regardless of targeting rules.                                            |

## Error codes

When an evaluation error occurs, the method returns the default value you provided. The `*Details` methods include additional metadata about the error.

| Error code       | Description                                                                                                                                                             |
| ---------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| TYPE\_MISMATCH   | The flag's variation type does not match the requested type. For example, calling getBooleanValue on a flag whose variation is a string. The default value is returned. |
| GENERAL          | An unexpected error occurred during evaluation (for example, a network failure). The default value is returned.                                                         |
| FLAG\_NOT\_FOUND | The specified flag key does not exist in the app. The default value is returned.                                                                                        |

## Example

The following example inspects evaluation details returned by `getBooleanDetails`:

* [  JavaScript ](#tab-panel-6865)
* [  TypeScript ](#tab-panel-6866)

JavaScript

```

const details = await env.FLAGS.getBooleanDetails("my-feature", false, {

  userId: "user-42",

});


switch (details.reason) {

  case "TARGETING_MATCH":

    console.log(`Matched targeting rule, variant: ${details.variant}`);

    break;

  case "SPLIT":

    console.log(`Included in rollout, variant: ${details.variant}`);

    break;

  case "DEFAULT":

    console.log("No rule matched, using default variation");

    break;

  case "DISABLED":

    console.log("Flag is disabled");

    break;

}


if (details.errorCode) {

  console.error(

    `Evaluation error: ${details.errorCode} - ${details.errorMessage}`,

  );

}


```

Explain Code

TypeScript

```

const details = await env.FLAGS.getBooleanDetails("my-feature", false, {

  userId: "user-42",

});


switch (details.reason) {

  case "TARGETING_MATCH":

    console.log(`Matched targeting rule, variant: ${details.variant}`);

    break;

  case "SPLIT":

    console.log(`Included in rollout, variant: ${details.variant}`);

    break;

  case "DEFAULT":

    console.log("No rule matched, using default variation");

    break;

  case "DISABLED":

    console.log("Flag is disabled");

    break;

}


if (details.errorCode) {

  console.error(

    `Evaluation error: ${details.errorCode} - ${details.errorMessage}`,

  );

}


```

Explain Code

```json
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```