144 files declare their use of FormBase

ActionAdminManageForm.php in core/modules/action/src/Form/ActionAdminManageForm.php
AddFormBase.php in core/modules/media_library/src/Form/AddFormBase.php
AjaxCssForm.php in core/modules/ckeditor/tests/modules/src/Form/AjaxCssForm.php
AjaxFormsTestAjaxElementsForm.php in core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestAjaxElementsForm.php
AjaxFormsTestCommandsForm.php in core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestCommandsForm.php
AjaxFormsTestImageButtonForm.php in core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestImageButtonForm.php
AjaxFormsTestLazyLoadForm.php in core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestLazyLoadForm.php
AjaxFormsTestSimpleForm.php in core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestSimpleForm.php
AjaxFormsTestValidationForm.php in core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestValidationForm.php
AjaxTestDialogForm.php in core/modules/system/tests/modules/ajax_test/src/Form/AjaxTestDialogForm.php
AjaxTestForm.php in core/modules/system/tests/modules/ajax_test/src/Form/AjaxTestForm.php
BanAdmin.php in core/modules/ban/src/Form/BanAdmin.php
BatchTestChainedForm.php in core/modules/system/tests/modules/batch_test/src/Form/BatchTestChainedForm.php
BatchTestMockForm.php in core/modules/system/tests/modules/batch_test/src/Form/BatchTestMockForm.php
BatchTestMultiStepForm.php in core/modules/system/tests/modules/batch_test/src/Form/BatchTestMultiStepForm.php
BatchTestSimpleForm.php in core/modules/system/tests/modules/batch_test/src/Form/BatchTestSimpleForm.php
BigPipeTestForm.php in core/modules/big_pipe/tests/modules/big_pipe_test/src/Form/BigPipeTestForm.php
BookAdminEditForm.php in core/modules/book/src/Form/BookAdminEditForm.php
CommentAdminOverview.php in core/modules/comment/src/Form/CommentAdminOverview.php
ConfigExportForm.php in core/modules/config/src/Form/ConfigExportForm.php
ConfigImportForm.php in core/modules/config/src/Form/ConfigImportForm.php
ConfigSingleExportForm.php in core/modules/config/src/Form/ConfigSingleExportForm.php
ConfigSync.php in core/modules/config/src/Form/ConfigSync.php
ConfigTranslationFormBase.php in core/modules/config_translation/src/Form/ConfigTranslationFormBase.php
ConfigureBlockFormBase.php in core/modules/layout_builder/src/Form/ConfigureBlockFormBase.php
ConfigureSectionForm.php in core/modules/layout_builder/src/Form/ConfigureSectionForm.php
ContentLanguageSettingsForm.php in core/modules/language/src/Form/ContentLanguageSettingsForm.php
ContentModerationConfigureEntityTypesForm.php in core/modules/content_moderation/src/Form/ContentModerationConfigureEntityTypesForm.php
CronForm.php in core/modules/system/src/Form/CronForm.php
DatabaseTestForm.php in core/modules/system/tests/modules/database_test/src/Form/DatabaseTestForm.php
DblogFilterForm.php in core/modules/dblog/src/Form/DblogFilterForm.php
EditorImageDialog.php in core/modules/editor/src/Form/EditorImageDialog.php
EditorLinkDialog.php in core/modules/editor/src/Form/EditorLinkDialog.php
EditorMediaDialog.php in core/modules/media/src/Form/EditorMediaDialog.php
EntityForm.php in core/lib/Drupal/Core/Entity/EntityForm.php
EntityModerationForm.php in core/modules/content_moderation/src/Form/EntityModerationForm.php
EntityResolverManagerTest.php in core/tests/Drupal/Tests/Core/Entity/EntityResolverManagerTest.php
Contains \Drupal\Tests\Core\Entity\EntityResolverManagerTest.
ExportForm.php in core/modules/locale/src/Form/ExportForm.php
FavoriteAnimalTestForm.php in core/modules/block/tests/modules/block_test/src/Form/FavoriteAnimalTestForm.php
FieldStorageAddForm.php in core/modules/field_ui/src/Form/FieldStorageAddForm.php
FileModuleTestForm.php in core/modules/file/tests/file_module_test/src/Form/FileModuleTestForm.php
FileTestSaveUploadFromForm.php in core/modules/file/tests/file_test/src/Form/FileTestSaveUploadFromForm.php
FileTransferAuthorizeForm.php in core/lib/Drupal/Core/FileTransfer/Form/FileTransferAuthorizeForm.php
FilterTestFormatForm.php in core/modules/filter/tests/filter_test/src/Form/FilterTestFormatForm.php
FormTestAlterForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestAlterForm.php
FormTestAutocompleteForm.php in core/modules/system/tests/modules/form_test/src/FormTestAutocompleteForm.php
FormTestButtonClassForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestButtonClassForm.php
FormTestCheckboxesRadiosForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestCheckboxesRadiosForm.php
FormTestCheckboxesZeroForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestCheckboxesZeroForm.php
FormTestCheckboxForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestCheckboxForm.php
FormTestCheckboxTypeJugglingForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestCheckboxTypeJugglingForm.php
FormTestClickedButtonForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestClickedButtonForm.php
FormTestColorForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestColorForm.php
FormTestDescriptionForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestDescriptionForm.php
FormTestDetailsForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestDetailsForm.php
FormTestDisabledElementsForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestDisabledElementsForm.php
FormTestEmailForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestEmailForm.php
FormTestEmptySelectForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestEmptySelectForm.php
FormTestFileForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestFileForm.php
FormTestFormStateValuesCleanAdvancedForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestFormStateValuesCleanAdvancedForm.php
FormTestFormStateValuesCleanForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestFormStateValuesCleanForm.php
FormTestGetForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestGetForm.php
FormTestGroupContainerForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestGroupContainerForm.php
FormTestGroupDetailsForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestGroupDetailsForm.php
FormTestGroupFieldsetForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestGroupFieldsetForm.php
FormTestGroupVerticalTabsForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestGroupVerticalTabsForm.php
FormTestInputForgeryForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestInputForgeryForm.php
FormTestLabelForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestLabelForm.php
FormTestLanguageSelectForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestLanguageSelectForm.php
FormTestLimitValidationErrorsForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestLimitValidationErrorsForm.php
FormTestMachineNameForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestMachineNameForm.php
FormTestMachineNameValidationForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestMachineNameValidationForm.php
FormTestNumberForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestNumberForm.php
FormTestOptionalContainerForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestOptionalContainerForm.php
FormTestPatternForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestPatternForm.php
FormTestPlaceholderForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestPlaceholderForm.php
FormTestProgrammaticForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestProgrammaticForm.php
FormTestRadiosCheckedForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestRadiosCheckedForm.php
FormTestRangeForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestRangeForm.php
FormTestRangeInvalidForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestRangeInvalidForm.php
FormTestRebuildPreserveValuesForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestRebuildPreserveValuesForm.php
FormTestRedirectForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestRedirectForm.php
FormTestRequiredAttributeForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestRequiredAttributeForm.php
FormTestResponseForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestResponseForm.php
FormTestSelectForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestSelectForm.php
FormTestStatePersistForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestStatePersistForm.php
FormTestStorageForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestStorageForm.php
FormTestStoragePageCacheForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestStoragePageCacheForm.php
FormTestTableSelectFormBase.php in core/modules/system/tests/modules/form_test/src/Form/FormTestTableSelectFormBase.php
FormTestUrlForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestUrlForm.php
FormTestValidateForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestValidateForm.php
FormTestValidateNoToken.php in core/modules/system/tests/modules/form_test/src/Form/FormTestValidateNoToken.php
FormTestValidateRequiredForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestValidateRequiredForm.php
FormTestValidateRequiredNoTitleForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestValidateRequiredNoTitleForm.php
FormTestVerticalTabsAccessForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestVerticalTabsAccessForm.php
FormTestVerticalTabsForm.php in core/modules/system/tests/modules/form_test/src/Form/FormTestVerticalTabsForm.php
ImageEffectFormBase.php in core/modules/image/src/Form/ImageEffectFormBase.php
ImportForm.php in core/modules/locale/src/Form/ImportForm.php
JavascriptStatesForm.php in core/modules/system/tests/modules/form_test/src/Form/JavascriptStatesForm.php
JsAjaxTestForm.php in core/modules/system/tests/modules/js_ajax_test/src/Form/JsAjaxTestForm.php
JsWebAssertTestForm.php in core/modules/system/tests/modules/js_webassert_test/src/Form/JsWebAssertTestForm.php
LanguageConfigurationElement.php in core/modules/language/tests/language_elements_test/src/Form/LanguageConfigurationElement.php
LanguageConfigurationElementTest.php in core/modules/language/tests/language_elements_test/src/Form/LanguageConfigurationElementTest.php
MenuLinkEditForm.php in core/modules/menu_ui/src/Form/MenuLinkEditForm.php
MigrateUpgradeFormBase.php in core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeFormBase.php
ModulesListForm.php in core/modules/system/src/Form/ModulesListForm.php
ModulesUninstallForm.php in core/modules/system/src/Form/ModulesUninstallForm.php
MoveBlockForm.php in core/modules/layout_builder/src/Form/MoveBlockForm.php
NestedEntityTestForm.php in core/modules/field/tests/modules/field_test/src/Form/NestedEntityTestForm.php
NodePreviewForm.php in core/modules/node/src/Form/NodePreviewForm.php
OpmlFeedAdd.php in core/modules/aggregator/src/Form/OpmlFeedAdd.php
OverviewTerms.php in core/modules/taxonomy/src/Form/OverviewTerms.php
PathFilterForm.php in core/modules/path/src/Form/PathFilterForm.php
QuickEditFieldForm.php in core/modules/quickedit/src/Form/QuickEditFieldForm.php
RedirectBlockForm.php in core/modules/system/tests/modules/form_test/src/Form/RedirectBlockForm.php
SearchBlockForm.php in core/modules/search/src/Form/SearchBlockForm.php
SearchEmbeddedForm.php in core/modules/search/tests/modules/search_embedded_form/src/Form/SearchEmbeddedForm.php
SearchPageForm.php in core/modules/search/src/Form/SearchPageForm.php
SelectLanguageForm.php in core/lib/Drupal/Core/Installer/Form/SelectLanguageForm.php
SelectProfileForm.php in core/lib/Drupal/Core/Installer/Form/SelectProfileForm.php
SessionTestForm.php in core/modules/system/tests/modules/session_test/src/Form/SessionTestForm.php
SimpletestResultsForm.php in core/modules/simpletest/src/Form/SimpletestResultsForm.php
SimpletestTestForm.php in core/modules/simpletest/src/Form/SimpletestTestForm.php
SiteSettingsForm.php in core/lib/Drupal/Core/Installer/Form/SiteSettingsForm.php
StubForm.php in core/modules/system/tests/src/Functional/Form/StubForm.php
SwitchShortcutSet.php in core/modules/shortcut/src/Form/SwitchShortcutSet.php
TableDragTestForm.php in core/modules/system/tests/modules/tabledrag_test/src/Form/TableDragTestForm.php
TestForm.php in core/modules/page_cache/tests/modules/src/Form/TestForm.php
TestForm.php in core/modules/system/tests/modules/test_page_test/src/Form/TestForm.php
TestForm.php in core/modules/block/tests/modules/block_test/src/Form/TestForm.php
TranslateFormBase.php in core/modules/locale/src/Form/TranslateFormBase.php
TranslationStatusForm.php in core/modules/locale/src/Form/TranslationStatusForm.php
UpdateManagerInstall.php in core/modules/update/src/Form/UpdateManagerInstall.php
UpdateManagerUpdate.php in core/modules/update/src/Form/UpdateManagerUpdate.php
UpdateReady.php in core/modules/update/src/Form/UpdateReady.php
UserLoginForm.php in core/modules/user/src/Form/UserLoginForm.php
UserPasswordForm.php in core/modules/user/src/Form/UserPasswordForm.php
UserPasswordResetForm.php in core/modules/user/src/Form/UserPasswordResetForm.php
UserPermissionsForm.php in core/modules/user/src/Form/UserPermissionsForm.php
ViewsExposedForm.php in core/modules/views/src/Form/ViewsExposedForm.php
ViewsFormBase.php in core/modules/views_ui/src/Form/Ajax/ViewsFormBase.php
ViewsTestDataElementEmbedForm.php in core/modules/views/tests/modules/views_test_data/src/Form/ViewsTestDataElementEmbedForm.php
ViewsTestDataElementForm.php in core/modules/views/tests/modules/views_test_data/src/Form/ViewsTestDataElementForm.php
WorkspaceSwitcherForm.php in core/modules/workspaces/src/Form/WorkspaceSwitcherForm.php

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