7 files declare their use of ConfigImporterException in Drupal 9

ConfigEntityStorage.php in core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php

ConfigImporterTest.php in core/tests/Drupal/KernelTests/Core/Config/ConfigImporterTest.php

ConfigImportRenameValidationTest.php in core/tests/Drupal/KernelTests/Core/Config/ConfigImportRenameValidationTest.php

ConfigSingleImportForm.php in core/modules/config/src/Form/ConfigSingleImportForm.php

ConfigSync.php in core/modules/config/src/Form/ConfigSync.php

ContentModerationWorkflowConfigTest.php in core/modules/content_moderation/tests/src/Kernel/ContentModerationWorkflowConfigTest.php

install.core.inc in core/includes/install.core.inc

API functions for installing Drupal.