> For the complete documentation index, see [llms.txt](https://dexiejs.typogram.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dexiejs.typogram.co/dexieerror/dexie.modifyerror.md).

# Dexie.ModifyError

#### Inheritance Hierarchy

* [Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)
  * Dexie.DexieError
    * Dexie.ModifyError

#### Description

Error that may occur in Collection.modify() and Collection.delete()

The methods that may throw this error can perform multiple operations on a collection. Therefore this error object will contain an array of the errors the occurred during the failed operations.

#### Properies

| failures     | Array of Error objects of all errors that have occurred                                                                                                                 |
| ------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| failedKeys   | Array of the keys of the failed modifications. This array will have the same order as failures so that failures\[i] will always represent the failure of failedKeys\[i] |
| successCount | Number of successful modifications made. NOTE: Only useful in case error is caught and transaction is not aborted.                                                      |

#### Properties derived from Error

[**message**](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/message)

[**name**](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/name)

#### Sample

```javascript
db.friends.where('name').startsWith('a').delete ()
    .catch(Dexie.ModifyError, function (err) {
        err.failures.forEach(function (failure) {
        console.error (failure.stack || failure.message);
    });
});
```

With yield

```javascript
db.transaction('rw', db.friends, function* ()=> {
    try {
        var numDeleted = yield db.friends
                                 .where('name').startsWithIgnoreCase('a')
                                 .delete();
    } catch (err) {
        if (err instanceof Dexie.ModifyError) {
            // Handle ModifyErrors explicitly
            err.failures.forEach(function (failure) {
            console.error (failure.stack || failure.message);
        } else {
            // Rethrow error of other types to ensure transaction is cancelled.
            throw e;
        }
    }
});
```