doctrine2/manual/new/docs/en/exceptions-and-warnings.txt

++ Manager exceptions

Doctrine_Manager_Exception is thrown if something failed at the connection management

<code type="php">
try {
    $manager->getConnection('unknown');
} catch (Doctrine_Manager_Exception) {
    // catch errors
}
</code>

++ Relation exceptions

thrown if something failed during the relation parsing

++ Connection exceptions

thrown if something failed at the database level

<code type="php">
try {
    $conn->execute('SELECT * FROM unknowntable');
} catch (Doctrine_Connection_Exception) {
    // catch errors
}
</code>

++ Query exceptions

thrown if DQL parsing fails somehow