diff --git a/library/Application/Configuration.php b/library/Application/Configuration.php
deleted file mode 100644
index 5dd3ce082..000000000
--- a/library/Application/Configuration.php
+++ /dev/null
@@ -1,313 +0,0 @@
-<?php
-
-/**
- * This file is part of OPUS. The software OPUS has been originally developed
- * at the University of Stuttgart with funding from the German Research Net,
- * the Federal Department of Higher Education and Research and the Ministry
- * of Science, Research and the Arts of the State of Baden-Wuerttemberg.
- *
- * OPUS 4 is a complete rewrite of the original OPUS software and was developed
- * by the Stuttgart University Library, the Library Service Center
- * Baden-Wuerttemberg, the Cooperative Library Network Berlin-Brandenburg,
- * the Saarland University and State Library, the Saxon State Library -
- * Dresden State and University Library, the Bielefeld University Library and
- * the University Library of Hamburg University of Technology with funding from
- * the German Research Foundation and the European Regional Development Fund.
- *
- * LICENCE
- * OPUS is free software; you can redistribute it and/or modify it under the
- * terms of the GNU General Public License as published by the Free Software
- * Foundation; either version 2 of the Licence, or any later version.
- * OPUS is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
- * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
- * details. You should have received a copy of the GNU General Public License
- * along with OPUS; if not, write to the Free Software Foundation, Inc., 51
- * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * @copyright   Copyright (c) 2008, OPUS 4 development team
- * @license     http://www.gnu.org/licenses/gpl.html General Public License
- */
-
-use Opus\Common\Config;
-use Opus\Common\LoggingTrait;
-
-/**
- * Klasse für das Laden von Übersetzungsressourcen.
- */
-class Application_Configuration extends Config
-{
-    use LoggingTrait;
-
-    /**
-     * Defaultsprache.
-     */
-    public const DEFAULT_LANGUAGE = 'en';
-
-    /**
-     * Unterstützte Sprachen.
-     *
-     * @var array
-     */
-    private $supportedLanguages;
-
-    /** @var string[] */
-    private $activatedLanguages;
-
-    /** @var bool Is language selection active in user interface. */
-    private $languageSelectionEnabled;
-
-    /** @var string */
-    private $defaultLanguage;
-
-    /** @var self */
-    private static $instance;
-
-    /**
-     * Returns instance of class.
-     *
-     * @return self
-     */
-    public static function getInstance()
-    {
-        if (self::$instance === null) {
-            self::$instance = new Application_Configuration();
-        }
-
-        return self::$instance;
-    }
-
-    /**
-     * Liefert die Konfiguration für Applikation.
-     *
-     * @return Zend_Config
-     */
-    public function getConfig()
-    {
-        return Config::get();
-    }
-
-    /**
-     * Returns name of repository.
-     *
-     * @return string
-     */
-    public function getName()
-    {
-        $config = $this->getConfig();
-
-        if (isset($config->name)) {
-            $name = $config->name;
-        } else {
-            $name = 'OPUS 4';
-        }
-
-        return $name;
-    }
-
-    /**
-     * Liefert die Sprachen, die von OPUS unterstützt werden.
-     *
-     * @return array
-     */
-    public function getSupportedLanguages()
-    {
-        if ($this->supportedLanguages === null) {
-            $config = $this->getConfig();
-            if (isset($config->supportedLanguages)) {
-                $this->supportedLanguages = array_map('trim', explode(',', $config->supportedLanguages));
-                /* TODO only used for debugging - remove?
-                $this->getLogger()->debug(
-                    Zend_Debug::dump(
-                        $this->_supportedLanguages, 'Supported languages ('
-                        . count($this->_supportedLanguages) . ')', false
-                    )
-                );*/
-            }
-        }
-        return $this->supportedLanguages;
-    }
-
-    /**
-     * @return string[]
-     */
-    public function getActivatedLanguages()
-    {
-        if ($this->activatedLanguages === null) {
-            $config = $this->getConfig();
-            if (isset($config->activatedLanguages)) {
-                $this->activatedLanguages = explode(',', $config->activatedLanguages);
-            } else {
-                return $this->getSupportedLanguages();
-            }
-        }
-
-        return $this->activatedLanguages;
-    }
-
-    /**
-     * Prüft, ob eine Sprache unterstützt wird.
-     *
-     * @param string $language Sprachcode (z.B. 'en')
-     * @return bool
-     */
-    public function isLanguageSupported($language)
-    {
-        $languages = $this->getSupportedLanguages();
-        return in_array($language, $languages);
-    }
-
-    /**
-     * Liefert Defaultsprache für Userinterface.
-     *
-     * @return string
-     */
-    public function getDefaultLanguage()
-    {
-        if ($this->defaultLanguage === null) {
-            $languages             = $this->getSupportedLanguages();
-            $this->defaultLanguage = $languages[0];
-
-            if ($this->isLanguageSelectionEnabled()) {
-                $locale   = new Zend_Locale();
-                $language = $locale->getDefault();
-                if (is_array($language) && count($language) > 0) {
-                    reset($language);
-                    $language = key($language);
-                } else {
-                    $language = self::DEFAULT_LANGUAGE;
-                }
-
-                if ($this->isLanguageSupported($language)) {
-                    $this->defaultLanguage = $language;
-                }
-            }
-        }
-
-        return $this->defaultLanguage;
-    }
-
-    /**
-     * Prüft, ob mehr als eine Sprache unterstützt wird.
-     *
-     * @return bool
-     */
-    public function isLanguageSelectionEnabled()
-    {
-        if ($this->languageSelectionEnabled === null) {
-            $this->languageSelectionEnabled = count($this->getSupportedLanguages()) > 1;
-        }
-        return $this->languageSelectionEnabled;
-    }
-
-    /**
-     * Returns path to files folder for document files.
-     *
-     * @return string Folder for storing document files
-     * @throws Application_Exception
-     */
-    public function getFilesPath()
-    {
-        return $this->getWorkspacePath() . 'files' . DIRECTORY_SEPARATOR;
-    }
-
-    /**
-     * Returns path to files folder for cached document files.
-     *
-     * @return string Folder for storing cached document files
-     * @throws Application_Exception
-     */
-    public function getFilecachePath()
-    {
-        return $this->getWorkspacePath() . 'filecache' . DIRECTORY_SEPARATOR;
-    }
-
-    /**
-     * Liest Inhalt von VERSION.txt um die installierte Opusversion zu ermitteln.
-     *
-     * @return string
-     */
-    public static function getOpusVersion()
-    {
-        $config       = Config::get();
-        $localVersion = $config->version;
-        return $localVersion ?? 'unknown';
-    }
-
-    /**
-     * Liefert Informationen als Key -> Value Paare in einem Array.
-     *
-     * @return array
-     */
-    public static function getOpusInfo()
-    {
-        return [];
-    }
-
-    /**
-     * Saves configuration as XML file.
-     *
-     * @param Zend_Config $update
-     * @throws Zend_Config_Exception
-     */
-    public static function save($update)
-    {
-        $config = self::load();
-
-        $config->merge($update);
-
-        $writer = new Zend_Config_Writer_Xml();
-        $writer->write(APPLICATION_PATH . '/application/configs/config.xml', $config);
-    }
-
-    /**
-     * @return Zend_Config_Xml
-     * @throws Zend_Config_Exception
-     */
-    public static function load()
-    {
-        return new Zend_Config_Xml(APPLICATION_PATH . '/application/configs/config.xml', null, true);
-    }
-
-    /**
-     * Returns value for key in current configuration.
-     *
-     * @param string $key Name of option
-     * @return string
-     */
-    public function getValue($key)
-    {
-        return $this->getValueFromConfig($this->getConfig(), $key);
-    }
-
-    /**
-     * Removes instance.
-     *
-     * This is used to reset the configuration to defaults in ini files.
-     */
-    public static function clearInstance()
-    {
-        self::$instance = null;
-    }
-
-    /**
-     * Returns Zend_Translate instance for application.
-     *
-     * @return Zend_Translate
-     * @throws Zend_Exception
-     */
-    public function getTranslate()
-    {
-        return Application_Translate::getInstance();
-    }
-
-    /**
-     * @return bool
-     */
-    public static function isUpdateInProgress()
-    {
-        $config = Config::get();
-
-        return isset($config->updateInProgress) && filter_var($config->updateInProgress, FILTER_VALIDATE_BOOLEAN);
-    }
-}
diff --git a/library/Application/Exception.php b/library/Application/Exception.php
deleted file mode 100644
index 811d0ea4e..000000000
--- a/library/Application/Exception.php
+++ /dev/null
@@ -1,57 +0,0 @@
-<?php
-
-/**
- * This file is part of OPUS. The software OPUS has been originally developed
- * at the University of Stuttgart with funding from the German Research Net,
- * the Federal Department of Higher Education and Research and the Ministry
- * of Science, Research and the Arts of the State of Baden-Wuerttemberg.
- *
- * OPUS 4 is a complete rewrite of the original OPUS software and was developed
- * by the Stuttgart University Library, the Library Service Center
- * Baden-Wuerttemberg, the Cooperative Library Network Berlin-Brandenburg,
- * the Saarland University and State Library, the Saxon State Library -
- * Dresden State and University Library, the Bielefeld University Library and
- * the University Library of Hamburg University of Technology with funding from
- * the German Research Foundation and the European Regional Development Fund.
- *
- * LICENCE
- * OPUS is free software; you can redistribute it and/or modify it under the
- * terms of the GNU General Public License as published by the Free Software
- * Foundation; either version 2 of the Licence, or any later version.
- * OPUS is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
- * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
- * details. You should have received a copy of the GNU General Public License
- * along with OPUS; if not, write to the Free Software Foundation, Inc., 51
- * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * @copyright   Copyright (c) 2008, OPUS 4 development team
- * @license     http://www.gnu.org/licenses/gpl.html General Public License
- */
-
-/**
- * TODO NAMESPACE change name
- */
-class Application_Exception extends Exception
-{
-    /** @var int */
-    protected $httpResponseCode;
-
-    /**
-     * @param int $code
-     * @return $this
-     */
-    public function setHttpResponseCode($code)
-    {
-        $this->httpResponseCode = $code;
-        return $this;
-    }
-
-    /**
-     * @return int
-     */
-    public function getHttpResponseCode()
-    {
-        return $this->httpResponseCode;
-    }
-}