Issue #2297875 by herom, bfr: Replace calls to form_set_error() to $form_state->setErrorByName().

core/includes/form.inc

core/modules/action/src/Plugin/Action/EmailAction.php

core/modules/color/color.module

...modules/content_translation/content_translation.admin.inc

core/modules/content_translation/content_translation.module

...les/content_translation/src/ContentTranslationHandler.php

core/modules/editor/editor.module

core/modules/file/file.module

core/modules/forum/forum.module

...odules/image/src/Plugin/ImageEffect/RotateImageEffect.php

...modules/image/src/Plugin/ImageEffect/ScaleImageEffect.php

core/modules/menu_ui/menu_ui.module

core/modules/node/node.api.php

core/modules/node/src/Plugin/Action/AssignOwnerNode.php

core/modules/rest/src/Plugin/views/row/DataFieldRow.php

core/modules/search/src/Plugin/views/filter/Search.php

core/modules/system/src/Plugin/views/field/BulkForm.php

core/modules/system/system.module

.../modules/system/tests/modules/form_test/src/Callbacks.php

...s/modules/form_test/src/Form/FormTestProgrammaticForm.php