# Preparations
* in IDE:
1. open the `core/units/configuration/configuration_event_handler.php` file for editing
2. add this code at the end of the `\ConfigurationEventHandler::OnBeforeItemValidate` method:
```
lang=php
if ( $object->GetDBField('VariableName') === 'UseColumnFreezer' ) {
$object->SetError('VariableValue', 'invalid_format');
}
```
3. save changes
# Part 1
# login to the Admin Console
# go to the {nav Configuration > Website > Advanced} section
# type different values for in the 1st and 2nd inputs of the `Root Password` system setting
# scroll to the top of the page
# press the `Save` toolbar button
# confirm, that:
* you're automatically scrolled to the 1st validation error
* validation error for the `Root Password` system setting is shown
# clear the inputs for the `Root Password` system setting
# scroll to the top of the page
# press the `Save` toolbar button
# confirm, that:
* you're automatically scrolled to the 1st validation error
* validation error for the `Use Column Freezer` system setting is shown
# Part 2
* in IDE:
# open the `core/units/sections/sections_config.php` file for editing
# change the template of the `in-portal:configure_advanced` section from the `config/config_universal` to `config/config_general`
# save changes
* in Admin Console:
# go to the {nav Tools > System Tools} section
# rebuild the section cache
# go to the {nav Configuration > Website > Advanced} section
# confirm, that the `Select Module Root Section` system setting is shown
# repeat test from the `Part 1` part starting from `item 2`
# Part 3
# login to the Admin Console
# go to the {nav Configuration > E-commerce > General} section
# change the `Select Module Root Section` system setting to any section/category, exception {nav Home > Products}
# save changes
# go to the {nav Configuration > E-commerce > General} section (through the item in the tree to ensure full page reload)
# confirm, that the `Select Module Root Section` system setting value was properly saved
# change the `Select Module Root Section` system setting to {nav Home > Products} section/category
# save changes