Problems with sqlsrv_errors in php

I am using PHP 5.6 on IIS 10 with SQL Server 2014, and I have the following function to make inserts, updates and deletes to the database:

<?php
public function ejecutarSQL($sql,$parametrosSQLServer=array()){
    $bandera=false;
    $msg="";
    $datos=array();
    $nowRows=0;
    $datos_pr=array();
    $cadena_replace="";
    if( $this->conexion){
        $parametros =array();
        if(count($parametrosSQLServer)>=1){
            foreach($parametrosSQLServer as $key => &$value) {
                $parametros[] = &$value;
            }
            $resultado=sqlsrv_prepare( $this->conexion,$sql,$parametros);
        }else{
            $resultado=sqlsrv_prepare( $this->conexion,$sql,$parametros);
        }
        $result= sqlsrv_execute($resultado);
        if($result != false){
            $nowRows=sqlsrv_rows_affected($resultado);
            if($nowRows ==1){
                $rst=sqlsrv_query($this->conexion,"SELECT @@IDENTITY AS ID ");
                $row =  sqlsrv_fetch_array($rst);
                if ($row["ID"] == null){
                    $datos[] =  "Registro exitoso";
                }else{
                    $datos[] =  $row["ID"];
                }
                sqlsrv_free_stmt($rst);
                $bandera=true;
                sqlsrv_free_stmt($resultado);
            }else{
                $bandera=false;
                $msg = sqlsrv_errors();//Esta linea siempre devuelve null aun con registros intencionalmente duplicados
                $nowRows=0;
                $msg=$msg[1]['message'];
                sqlsrv_free_stmt($resultado);
            }
        }else{
            $bandera= false;
            $nowRows=0;
            $msg = sqlsrv_errors();
            $msg=$msg[0]['message'];
        }
    }
    if ($bandera==true){
        return array(true, $nowRows, $datos);
    }else{
        return array(false, $nowRows, $msg);
    }
}

The code works correctly to do the operations. What does not work correctly is the sqlsrv_errors () function since when sending inserts with duplicate records, this function always returns null, and I can not see a description of the error (which I need).

I read that sqlsrv_errors () only returns errors and not warnings, so I modified the configuration so that I returned the warnings as errors, but the problem continues:

$this->datosConexion=@parse_ini_file($rutaProperties, false, INI_SCANNER_RAW);
    $this->schema=$this->datosConexion["SsqlsvrSchema"];
    $this->serverName = $this->datosConexion["SsqlsvrNombreServidor"]."\MSSQLSERVER,".$this->datosConexion["SsqlsvrPuerto"];
    $this->parametros = array( "Database"=> $this->datosConexion["SsqlsvrBaseDatos"] ,"UID"=> $this->datosConexion["SsqlsvrUsuario"] , "PWD"=>$this->datosConexion["SsqlsvrPass"], "CharacterSet" => "UTF-8");
    sqlsrv_configure('WarningsReturnAsErrors',0);//Esta es la linea que agregue
    $this->conexion = sqlsrv_connect( $this->serverName, $this->parametros);
    if($this->conexion) {
        return (true);
    }else{
         return(false);
    }

Does anyone know how to solve it? Will it be php.ini configuration?