Exceptions
PHP Manual

The MongoDuplicateKeyException class

(PECL mongo >= 1.5.0)

Introduction

Thrown when attempting to insert a document into a collection which already contains the same values for the unique keys.

Class synopsis

MongoDuplicateKeyException extends MongoWriteConcernException {
/* Inherited properties */
protected string $message ;
protected int $code ;
protected string $file ;
protected int $line ;
/* Inherited methods */
}

Examples

Example #1 Catching MongoDuplicateKeyException

<?php
$mc 
= new MongoClient("localhost");

$c $mc->selectCollection("test""test");

$c->insert(array('_id' => 1));
try {
    
$c->insert(array('_id' => 1));
} catch (
MongoWriteConcernException $e) {
    echo 
$e->getMessage(), "\n";
}
?>

The above examples will output something similar to:

localhost:27017: insertDocument :: caused by :: 11000 E11000 duplicate key error index: test.test.$_id_  dup key: { : 1 }

Exceptions
PHP Manual