I had a version 1.2.3 and I tried to upgrade to V1.3.1

On com_comprofiler.zip installation in backend, it went ok through first step, then on second step stopped on white page.

Activating error log, I trapped the message :

Fatal error: Cannot redeclare _PEAR_call_destructors() (previously declared in C:\wamp\www\sitejoomla\libraries\pear\PEAR.php:773) in C:\wamp\www\sitejoomla\administrator\components\com_comprofiler\library\pear\pear.php on line 811

Seems to be a conflict between these 2 declarations:

CB code :
[code:1]function _PEAR_call_destructors()
{
global $_PEAR_destructor_object_list;
if (is_array($_PEAR_destructor_object_list) &&
sizeof($_PEAR_destructor_object_list))
{
reset($_PEAR_destructor_object_list);
if (PEAR_ZE2) {
$destructLifoExists = PEAR5::getStaticProperty('PEAR', 'destructlifo');
} else {
$destructLifoExists = PEAR::getStaticProperty('PEAR', 'destructlifo');
}

if ($destructLifoExists) {
$_PEAR_destructor_object_list = array_reverse($_PEAR_destructor_object_list);
}

while (list($k, $objref) = each($_PEAR_destructor_object_list)) {
$classname = get_class($objref);
while ($classname) {
$destructor = "_$classname";
if (method_exists($objref, $destructor)) {
$objref->$destructor();
break;
} else {
$classname = get_parent_class($classname);
}
}
}
// Empty the object list to ensure that destructors are
// not called more than once.
$_PEAR_destructor_object_list = array();
}

// Now call the shutdown functions
if (isset($GLOBALS) AND is_array($GLOBALS) AND !empty($GLOBALS)) {
foreach ($GLOBALS as $value) {
call_user_func_array($value[0], $value[1]);
}
}
}[/code:1]

Joomla library
[code:1]
function _PEAR_call_destructors()
{
global $_PEAR_destructor_object_list;
if (is_array($_PEAR_destructor_object_list) &&
sizeof($_PEAR_destructor_object_list))
{
reset($_PEAR_destructor_object_list);
if (PEAR_ZE2) {
$destructLifoExists = PEAR5::getStaticProperty('PEAR', 'destructlifo');
} else {
$destructLifoExists = PEAR::getStaticProperty('PEAR', 'destructlifo');
}

if ($destructLifoExists) {
$_PEAR_destructor_object_list = array_reverse($_PEAR_destructor_object_list);
}

while (list($k, $objref) = each($_PEAR_destructor_object_list)) {
$classname = get_class($objref);
while ($classname) {
$destructor = "_$classname";
if (method_exists($objref, $destructor)) {
$objref->$destructor();
break;
} else {
$classname = get_parent_class($classname);
}
}
}
// Empty the object list to ensure that destructors are
// not called more than once.
$_PEAR_destructor_object_list = array();
}
[/code:1]

thanks, I'll have a try. By third party plugins, do you actually mean plugins or modules also ?

Problem solved!
Thank you, your tip worked. 3rd party plugin was Yvxxx (smiley and comments), which I use for enhanced interactivity on my site.
I have reactivated them after CB upgrade, it looks fine.