Class 'Exception' not found in downloader/pearlib/php/PEAR/Frontend.php on line 91

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or fails with the following error message:

Class 'Exception' not found in downloader/pearlib/php/PEAR/Frontend.php on line 91


or

Assigning the return value of new by reference is deprecated  in downloader/pearlib/php/PEAR/Frontend.php on line 91

or

Warning: Parameter 3 to PEAR_Task_Replace::validateXml() expected to be a reference,

 value given in downloader/pearlib/php/PEAR/PackageFile/v2/Validator.php on line 1143

It is Magento 1.3 or early Magento 1.4.0 release running on server with PHP 5.3 version.

The reason of the error message is deprecated functions used in the old Magento Pear code. To let it work the following changes can be used:

• edit downloader/pearlib/php/PEAR/PackageFile/v2/Validator.php and changle line 1143 from
  $ret = call_user_func(array($tagClass, ‘validateXml’), $this->_pf, $v, $this->_pf->_config, $save);

  to

  $ret = call_user_func(array($tagClass, ‘validateXml’), $this->_pf, $v, array(&$this->_pf->_config), $save);

• edit downloader/pearlib/php/PEAR/Frontend.php and change line 91 from
  $obj = &new $uiclass;
  to
  $obj = new $uiclass;
• alternatively, edit the following files:
  • downloader/Maged/Pear.php
  • lib/Varien/Pear.php
    and change error_reporting function from
    error_reporting(E_ALL & ~E_NOTICE);
    to
    error_reporting(E_ALL & ~E_NOTICE & ~E_DEPRECATED);