29 files declare their use of FileException in Drupal 9

AssetDumper.php in core/lib/Drupal/Core/Asset/AssetDumper.php

color.module in core/modules/color/color.module

Allows users to change the color scheme of themes.

ConfigController.php in core/modules/config/src/Controller/ConfigController.php

ConfigInstallWebTest.php in core/modules/config/tests/src/Functional/ConfigInstallWebTest.php

DirectoryTest.php in core/tests/Drupal/KernelTests/Core/File/DirectoryTest.php

file.module in core/modules/file/file.module

Defines a "managed_file" Form API field and a "file" field for Field module.

File.php in core/modules/file/src/Entity/File.php

FileCopy.php in core/modules/migrate/src/Plugin/migrate/process/FileCopy.php

FileMoveTest.php in core/tests/Drupal/KernelTests/Core/File/FileMoveTest.php

FileSystem.php in core/lib/Drupal/Core/File/FileSystem.php

FileSystemTest.php in core/tests/Drupal/Tests/Core/File/FileSystemTest.php

FileSystemTest.php in core/tests/Drupal/KernelTests/Core/File/FileSystemTest.php

FileUploadResource.php in core/modules/file/src/Plugin/rest/resource/FileUploadResource.php

GDToolkit.php in core/modules/system/src/Plugin/ImageToolkit/GDToolkit.php

image.install in core/modules/image/image.install

Install, update and uninstall functions for the image module.

ImageItem.php in core/modules/image/src/Plugin/Field/FieldType/ImageItem.php

ImageStyle.php in core/modules/image/src/Entity/ImageStyle.php

InstallHelper.php in core/profiles/demo_umami/modules/demo_umami_content/src/InstallHelper.php

locale.bulk.inc in core/modules/locale/locale.bulk.inc

Mass import-export and batch import functionality for Gettext .po files.

locale.install in core/modules/locale/locale.install

Install, update, and uninstall functions for the Locale module.

locale.module in core/modules/locale/locale.module

Enables the translation of the user interface to languages other than English.

media.install in core/modules/media/media.install

Install, uninstall and update hooks for Media module.

OEmbed.php in core/modules/media/src/Plugin/media/Source/OEmbed.php

simpletest.install in core/modules/simpletest/simpletest.install

Uninstall functions for the simpletest module.

system.module in core/modules/system/system.module

Configuration system that lets administrators modify the workings of the site.

TemporaryJsonapiFileFieldUploader.php in core/modules/jsonapi/src/Controller/TemporaryJsonapiFileFieldUploader.php

ThemeSettingsForm.php in core/modules/system/src/Form/ThemeSettingsForm.php

update.manager.inc in core/modules/update/update.manager.inc

Administrative screens and processing functions of the Update Manager module.

update.module in core/modules/update/update.module

Handles updates of Drupal core and contributed projects.