Fatal error after upgrading from 20.1.1 to 20.8 when clearing cache from Admin Page

[samex]

After upgrading OpenMage from version 20.1.1 to 20.8, I encountered a fatal error when attempting to clear the cache from the Admin Page.

Environment:

1. OpenMage 20.8
2. PHP Version 7.4.28, Apache, MariaDB

Reproduce

1. Update OpenMage from version 20.1.1 to 20.8.
2. Flush the cache from the admin page.

Expected

1. Cache should be cleared without errors.
2. Website should function correctly.

Actual result

1. Error message is displayed on any page:

   
   Fatal error:  Uncaught Error: Call to undefined method Mage_Core_Model_Config::getCacheSaveLock() in /app/htdocs/app/code/core/Mage/Core/Model/App.php:436
   Stack trace:
   #0 /app/htdocs/app/code/core/Mage/Core/Model/App.php(347): Mage_Core_Model_App->_initModules()
   # 1 /app/htdocs/app/Mage.php(761): Mage_Core_Model_App->run(Array)
   # 2 /app/htdocs/index.php(56): Mage::run('', 'store')
   # 3 {main}

Next Error: Call to undefined method Mage_Core_Model_Config::releaseCacheSaveLock() in /app/htdocs/app/code/core/Mage/Core/Model/App.php:449 Stack trace:

0 /app/htdocs/app/code/core/Mage/Core/Model/App.php(347): Mage_Core_Model_App->_initModules()

1 /app/htdocs/app/Mage.php(761): Mage_Core_Model_App->run(Array)

2 /app/htdocs/index.php(56): Mage::run('', 'store')

3 {main}

thrown in /app/htdocs/app/code/core/Mage/Core/Model/App.php on line 449

Workaround: 

**If the cache is flushed from CLI, the site works correctly, but clearing the cache from the admin page results in the above error.**

I have tried using PHP 8.2, but encountered numerous errors with third-party modules that need to be resolved. PHP 7.4 still seems to work for now.

[fballiano]

I can't reproduce the error on a fresh install

the method is in the correct file

do you have something in app/code/local/Mage overriding core files?

[samex]

Thank you for your quick and accurate response. Indeed, I had core files in the code/local directory. I deleted them, and now it is working as expected. Thanks again!