Upgrade problem

[eluser]shinokada[/eluser]
The book Professional Codeigniter comes with sample codes.

I assume codes are based on the previous version of CI.

I hacked some problems and working fine.

So I copied and pased new library files from CI 1.7.2.

Then I get the following errors.

+++++++++
A PHP Error was encountered

Severity: Notice

Message: Undefined property: CI_Router::$uri_string

Filename: libraries/Output.php

Line Number: 359
A PHP Error was encountered

Severity: Warning

Message: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at C:\xampp\htdocs\codeigniter_shopping\system\libraries\Exceptions.php:166)

Filename: controllers/welcome.php

Line Number: 6

++++++++++++

The welcome.php has the following lines around line 6.

Code:

class Welcome extends Controller {
  function Welcome(){
    parent::Controller();
    session_start();
    $this->output->enable_profiler(FALSE);
  }

I deleted session_start();

Then it gives the following errors.

++++++++++++++++++++

A PHP Error was encountered

Severity: Notice

Message: Undefined property: CI_Router::$uri_string

Filename: libraries/Output.php

Line Number: 359
A PHP Error was encountered

Severity: Warning

Message: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\codeigniter_shopping_ori\system\libraries\Exceptions.php:166)

Filename: libraries/Session.php

Line Number: 662

+++++++++++++++++++

Is there any other files do I need upgrade?

Thanks in advance.

Sorry for bothering you.
I updated all the files and it is ok now.