sakana

Expressフォーム投稿時のエラーについて

こんにちは。初めて投稿いたします。
よろしくお願いいたします。

Expressオブジェクトを使って、ページ内にExpressフォームを作成しましたところ

http://concrete5-japan.org/community/forums/development/post-16817/

投稿の際に上記スレッドと同じエラーが表示されました。
jinbouchaさまの投稿を参考にしながらコードを改変してみましたが、今度は

Error Interface 'Application\Concrete\Express\Entry\Notifier\NotificationInterface' not found

というエラーが表示され、困り果てております。
パスは何度も確認して、ファイルも当該箇所にございます。
同じようなご経験のある方、お知恵を拝借できませんでしょうか？

# concrete5 Version
Core Version - 8.5.2
Version Installed - 8.5.2
Database Version - 20190925072210

# Database Information
Version: 5.7.29-log
SQL Mode: NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION

# concrete5 Packages
None

# concrete5 Overrides
blocks/external_form/form/controller/entry_form2.php, blocks/external_form/form/controller/entry_form.php, blocks/external_form/form/controller/entry_form_test.php, blocks/external_form/form/controller, blocks/external_form/form/entry_form2.php, blocks/external_form/form/entry_form.php, blocks/external_form/form/entry_form_test.php, blocks/external_form/form/entry_form2 copy.php, blocks/external_form/form, blocks/external_form, blocks/form/templates/fileattach/view.php, blocks/form/templates/fileattach/view.css, blocks/form/templates/fileattach, blocks/form/templates, blocks/form, blocks/express_form/controller.php, blocks/express_form/db.xml, blocks/express_form/icon.png, blocks/express_form/view.php, blocks/express_form/templates/faq.php, blocks/express_form/templates, blocks/express_form, attributes/user_selector/controller.php, attributes/user_selector/form.php, attributes/user_selector, mail/block_external_form_entry_apply_admin.php, mail/block_external_form_entry_apply_user.php, mail/block_external_form_entry2_apply_user.php, mail/block_external_form_entry2_apply_admin.php, single_pages/login.php, single_pages/members/directory.php, single_pages/members/profile.php, single_pages/members/view.php, single_pages/members, themes/jsjt/page_forbidden.php, themes/jsjt/right_sidebar.php, themes/jsjt/css/styles.xml, themes/jsjt/css/bootstrap-modified.css, themes/jsjt/css/build/blocks/testimonial.less, themes/jsjt/css/build/blocks/date-navigation.less, themes/jsjt/css/build/blocks/page-list.less, themes/jsjt/css/build/blocks/image.less, themes/jsjt/css/build/blocks/page-title-option-byline.less, themes/jsjt/css/build/blocks/feature-template-hover-description.less, themes/jsjt/css/build/blocks/image-slider.less, themes/jsjt/css/build/blocks/topic-list.less, themes/jsjt/css/build/blocks/page-attribute-display.less, themes/jsjt/css/build/blocks/tags.less, themes/jsjt/css/build/blocks/page-title.less, themes/jsjt/css/build/blocks/next-previous.less, 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themes/jsjt/css/build/bootstrap-3.4.1/mixins/text-emphasis.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/nav-vertical-align.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/table-row.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/hide-text.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/grid.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/gradients.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/nav-divider.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/buttons.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/list-group.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/image.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/reset-filter.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/text-overflow.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/size.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/background-variant.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/pagination.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/center-block.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/responsive-visibility.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/labels.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/grid-framework.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/border-radius.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/clearfix.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/opacity.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/alerts.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/progress-bar.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/vendor-prefixes.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/reset-text.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/resize.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/panels.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins/tab-focus.less, themes/jsjt/css/build/bootstrap-3.4.1/mixins, themes/jsjt/css/build/bootstrap-3.4.1/carousel.less, themes/jsjt/css/build/bootstrap-3.4.1/print.less, themes/jsjt/css/build/bootstrap-3.4.1/buttons.less, themes/jsjt/css/build/bootstrap-3.4.1/list-group.less, themes/jsjt/css/build/bootstrap-3.4.1/navbar.less, themes/jsjt/css/build/bootstrap-3.4.1/button-groups.less, themes/jsjt/css/build/bootstrap-3.4.1/progress-bars.less, themes/jsjt/css/build/bootstrap-3.4.1/bootstrap.less, themes/jsjt/css/build/bootstrap-3.4.1/glyphicons.less, themes/jsjt/css/build/bootstrap-3.4.1/variables.less, themes/jsjt/css/build/bootstrap-3.4.1/jumbotron.less, themes/jsjt/css/build/bootstrap-3.4.1/responsive-embed.less, themes/jsjt/css/build/bootstrap-3.4.1/badges.less, themes/jsjt/css/build/bootstrap-3.4.1/pagination.less, themes/jsjt/css/build/bootstrap-3.4.1/pager.less, themes/jsjt/css/build/bootstrap-3.4.1/input-groups.less, themes/jsjt/css/build/bootstrap-3.4.1/type.less, themes/jsjt/css/build/bootstrap-3.4.1/normalize.less, themes/jsjt/css/build/bootstrap-3.4.1/theme.less, themes/jsjt/css/build/bootstrap-3.4.1/code.less, 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themes/jsjt/css/build/fonts/blue-sky.less, themes/jsjt/css/build/fonts/night-road.less, themes/jsjt/css/build/fonts/royal.less, themes/jsjt/css/build/fonts/defaults.less, themes/jsjt/css/build/fonts, themes/jsjt/css/build/custom-design-classes/block-sidebar-padded.less, themes/jsjt/css/build/custom-design-classes/testimonial-bio.less, themes/jsjt/css/build/custom-design-classes/block-sidebar-wrapped.less, themes/jsjt/css/build/custom-design-classes/area-content-accent.less, themes/jsjt/css/build/custom-design-classes/blog-entry-list.less, themes/jsjt/css/build/custom-design-classes/recent-blog-entry.less, themes/jsjt/css/build/custom-design-classes, themes/jsjt/css/build/mixins.less, themes/jsjt/css/build/breadcrumb.less, themes/jsjt/css/build/miscellaneous-styles.less, themes/jsjt/css/build, themes/jsjt/css/presets/blue-sky.less, themes/jsjt/css/presets/night-road.less, themes/jsjt/css/presets/royal.less, themes/jsjt/css/presets/defaults.less, themes/jsjt/css/presets, themes/jsjt/css/main.less, themes/jsjt/css/jsjt.less, themes/jsjt/css, themes/jsjt/images/background-slider-night-road.png, themes/jsjt/images/background-slider-blue-sky.png, themes/jsjt/images/background-slider-royal.png, themes/jsjt/images/background-slider-default.png, themes/jsjt/images/background.png, themes/jsjt/images/mainbg.png, themes/jsjt/images/contentbg.png, themes/jsjt/images, themes/jsjt/blank.php, themes/jsjt/page_theme.php, themes/jsjt/page_not_found.php, themes/jsjt/left_sidebar.php, themes/jsjt/elements/footer_bottom.php, themes/jsjt/elements/header_top.php, themes/jsjt/elements/header.php, themes/jsjt/elements/footer.php, themes/jsjt/elements/header_nobtn.php, themes/jsjt/elements, themes/jsjt/view.php, themes/jsjt/thumbnail.png, themes/jsjt/default.php, themes/jsjt/full.php, themes/jsjt/entry.php, themes/jsjt/js/alert/alert.js, themes/jsjt/js/alert/alert.php, themes/jsjt/js/alert, themes/jsjt/js/entry_form.js, themes/jsjt/js, themes/jsjt, src/Concrete/Express/Entry/Notifier/Notification/AbstractFormBlockSubmissionNotification.php, src/Concrete/Express/Entry/Notifier/Notification/FormBlockSubmissionEmailNotification.php, src/Concrete/Express/Entry/Notifier/Notification/FormBlockSubmissionNotification.php, src/Concrete/Express/Entry/Notifier/Notification, src/Concrete/Express/Entry/Notifier/AbstractNotifier.php, src/Concrete/Express/Entry/Notifier/NotifierInterface.php, src/Concrete/Express/Entry/Notifier, src/Concrete/Express/Entry, src/Concrete/Express, src/Concrete

# concrete5 Cache Settings
Block Cache - Off
Overrides Cache - Off
Full Page Caching - Off
Full Page Cache Lifetime - Every 6 hours (default setting).

# Server Software
Apache

# Server API
apache2handler

# PHP Version
7.4.10

# PHP Extensions
apache2handler, apcu, Core, ctype, curl, date, dom, exif, fileinfo, filter, ftp, gd, gettext, gmp, hash, iconv, intl, json, libxml, mbstring, mcrypt, mysqli, mysqlnd, openssl, pcre, PDO, pdo_mysql, pdo_sqlite, Phar, posix, Reflection, session, SimpleXML, snmp, soap, SPL, sqlite3, standard, tokenizer, xml, xmlreader, xmlwriter, xsl, Zend OPcache, zip, zlib

# PHP Settings
max_execution_time - 30
log_errors_max_len - 1024
max_file_uploads - 20
max_input_nesting_level - 64
max_input_time - -1
max_input_vars - 1000
memory_limit - 128M
post_max_size - 100M
upload_max_filesize - 50M
mbstring.regex_retry_limit - 1000000
mbstring.regex_stack_limit - 100000
mysqli.max_links - Unlimited
mysqli.max_persistent - Unlimited
pcre.backtrack_limit - 1000000
pcre.recursion_limit - 100000
session.cache_limiter - no value
session.gc_maxlifetime - 7200
soap.wsdl_cache_limit - 5
unserialize_max_depth - 4096
opcache.max_accelerated_files - 10000
opcache.max_file_size - 0
opcache.max_wasted_percentage - 5