Deprecated functionality: strlen(): Passing null to parameter #1 ($string) of type string is deprecated

[ADDISON74]

OpenMage 20.3.0
Magento Sample Pack
PHP 8.3
MAGE_IS_DEVELOPER_MODE=1

Steps to reproduce this issue

1 - Go to the Backend > System > Import / Export > Dataflow Profiles
2 - Click/Edit on any of the listed profiles. In my case there are 6 profiles

You will get this error

Deprecated functionality: strlen(): Passing null to parameter #1 ($string) of type string is deprecated  in /var/www/html/app/code/core/Mage/Adminhtml/Block/System/Convert/Gui/Edit/Tab/Wizard.php on line 95

#0 /var/www/html/app/code/core/Mage/Adminhtml/Block/System/Convert/Gui/Edit/Tab/Wizard.php(95): mageCoreErrorHandler()
#1 /var/www/html/app/design/adminhtml/default/default/template/system/convert/profile/wizard.phtml(220): Mage_Adminhtml_Block_System_Convert_Gui_Edit_Tab_Wizard->getValue()
#2 /var/www/html/app/code/core/Mage/Core/Block/Template.php(273): include('...')
#3 /var/www/html/app/code/core/Mage/Core/Block/Template.php(310): Mage_Core_Block_Template->fetchView()
#4 /var/www/html/app/code/core/Mage/Core/Block/Template.php(323): Mage_Core_Block_Template->renderView()
#5 /var/www/html/app/code/core/Mage/Adminhtml/Block/Template.php(67): Mage_Core_Block_Template->_toHtml()
#6 /var/www/html/app/code/core/Mage/Adminhtml/Block/Widget/Container.php(293): Mage_Adminhtml_Block_Template->_toHtml()
#7 /var/www/html/app/code/core/Mage/Core/Block/Abstract.php(926): Mage_Adminhtml_Block_Widget_Container->_toHtml()
#8 /var/www/html/app/code/core/Mage/Adminhtml/Block/System/Convert/Gui/Edit/Tabs.php(47): Mage_Core_Block_Abstract->toHtml()
#9 /var/www/html/app/code/core/Mage/Core/Block/Abstract.php(925): Mage_Adminhtml_Block_System_Convert_Gui_Edit_Tabs->_beforeToHtml()
#10 /var/www/html/app/code/core/Mage/Core/Block/Text/List.php(35): Mage_Core_Block_Abstract->toHtml()
#11 /var/www/html/app/code/core/Mage/Core/Block/Abstract.php(926): Mage_Core_Block_Text_List->_toHtml()
#12 /var/www/html/app/code/core/Mage/Core/Block/Abstract.php(643): Mage_Core_Block_Abstract->toHtml()
#13 /var/www/html/app/code/core/Mage/Core/Block/Abstract.php(587): Mage_Core_Block_Abstract->_getChildHtml()
#14 /var/www/html/app/design/adminhtml/default/default/template/page.phtml(47): Mage_Core_Block_Abstract->getChildHtml()
#15 /var/www/html/app/code/core/Mage/Core/Block/Template.php(273): include('...')
#16 /var/www/html/app/code/core/Mage/Core/Block/Template.php(310): Mage_Core_Block_Template->fetchView()
#17 /var/www/html/app/code/core/Mage/Core/Block/Template.php(323): Mage_Core_Block_Template->renderView()
#18 /var/www/html/app/code/core/Mage/Adminhtml/Block/Template.php(67): Mage_Core_Block_Template->_toHtml()
#19 /var/www/html/app/code/core/Mage/Core/Block/Abstract.php(926): Mage_Adminhtml_Block_Template->_toHtml()
#20 /var/www/html/app/code/core/Mage/Core/Model/Layout.php(573): Mage_Core_Block_Abstract->toHtml()
#21 /var/www/html/app/code/core/Mage/Core/Controller/Varien/Action.php(390): Mage_Core_Model_Layout->getOutput()
#22 /var/www/html/app/code/core/Mage/Adminhtml/controllers/System/Convert/GuiController.php(103): Mage_Core_Controller_Varien_Action->renderLayout()
#23 /var/www/html/app/code/core/Mage/Core/Controller/Varien/Action.php(421): Mage_Adminhtml_System_Convert_GuiController->editAction()
#24 /var/www/html/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(255): Mage_Core_Controller_Varien_Action->dispatch()
#25 /var/www/html/app/code/core/Mage/Core/Controller/Varien/Front.php(181): Mage_Core_Controller_Varien_Router_Standard->match()
#26 /var/www/html/app/code/core/Mage/Core/Model/App.php(358): Mage_Core_Controller_Varien_Front->dispatch()
#27 /var/www/html/app/Mage.php(760): Mage_Core_Model_App->run()
#28 /var/www/html/index.php(56): Mage::run()
#29 {main}

This is the PHP file and the line:

/app/code/core/Mage/Adminhtml/Block/System/Convert/Gui/Edit/Tab/Wizard.php on line 95

The same error appears if you click the [Add New Profile] button

[ADDISON74]

This issue involves several files that need to be modified.

In the Profiles page, this one with the grid, if we press the [Add New Profile] we get the error mentioned in the initial post. In the closed PR you changed the file correctly

/app/code/core/Mage/Adminhtml/Block/System/Convert/Gui/Edit/Tab/Wizard.php

Line 95

        if ($value === null) {
            return $default;
        }

With this change, we get the page where we can create a new profile. If we fill in the "Name" and press any of the [Save] buttons, another error will appear at the top

Deprecated functionality: strlen(): Passing null to parameter #1 ($string) of type string is deprecated in /var/www/html/app/code/core/Mage/Dataflow/Model/Profile.php on line 89

[ADDISON74]

I would fix that deprecated error as follows

/app/code/core/Mage/Dataflow/Model/Profile.php
Line 89

BEFORE

        if (strlen($actionsXML) < 0 &&

AFTER

        if (strlen($actionsXML ?? '') < 0 &&

The two changes seem to solve this issue.