diff --git a/packages/core/dev-test/backends/proxy/config.yml b/packages/core/dev-test/backends/proxy/config.yml
index fbebe0db..77021776 100644
--- a/packages/core/dev-test/backends/proxy/config.yml
+++ b/packages/core/dev-test/backends/proxy/config.yml
@@ -504,7 +504,7 @@ collections:
                 name: file
                 widget: file
   - name: i18n_playground
-    label: i18n Playground
+    label: i18n (Multiple Files)
     i18n: true
     folder: packages/core/dev-test/backends/proxy/_i18n_playground
     identifier_field: slug
@@ -524,6 +524,54 @@ collections:
         label: Date
         widget: datetime
         i18n: duplicate
+  - name: i18n_playground_multiple_folders
+    label: i18n (Multiple Folders)
+    i18n:
+      structure: multiple_folders
+      locales: [en, de, fr]
+      defaultLocale: en
+    folder: packages/core/dev-test/backends/proxy/_i18n_playground_multiple_folders
+    identifier_field: slug
+    create: true
+    fields:
+      # The slug field will be omitted from the translation.
+      - name: slug
+        label: Slug
+        widget: string
+      # same as 'i18n: translate'. Allows translation of the description field
+      - name: description
+        label: Description
+        widget: text
+        i18n: true
+      # The date field will be duplicated from the default locale.
+      - name: date
+        label: Date
+        widget: datetime
+        i18n: duplicate
+  - name: i18n_playground_single_file
+    label: i18n (Single File)
+    i18n:
+      structure: single_file
+      locales: [en, de, fr]
+      defaultLocale: en
+    folder: packages/core/dev-test/backends/proxy/_i18n_playground_multiple_folders
+    identifier_field: slug
+    create: true
+    fields:
+      # The slug field will be omitted from the translation.
+      - name: slug
+        label: Slug
+        widget: string
+      # same as 'i18n: translate'. Allows translation of the description field
+      - name: description
+        label: Description
+        widget: text
+        i18n: true
+      # The date field will be duplicated from the default locale.
+      - name: date
+        label: Date
+        widget: datetime
+        i18n: duplicate
   - name: pages
     label: Nested Pages
     label_singular: 'Page'
diff --git a/packages/core/src/__tests__/testConfig.ts b/packages/core/src/__tests__/testConfig.ts
index 070d8bd5..3494fcaf 100644
--- a/packages/core/src/__tests__/testConfig.ts
+++ b/packages/core/src/__tests__/testConfig.ts
@@ -1794,6 +1794,62 @@ const testConfig: Config<RelationKitchenSinkPostField> = {
         },
       ],
     },
+    {
+      name: 'i18n_playground_multiple_folders',
+      label: 'i18n (Multiple Folders)',
+      i18n: {
+        structure: 'multiple_folders',
+        locales: ['en', 'de', 'fr'],
+        defaultLocale: 'en',
+      },
+      folder: 'packages/core/dev-test/backends/proxy/_i18n_playground_multiple_folders',
+      identifier_field: 'slug',
+      create: true,
+      fields: [
+        {
+          name: 'slug',
+          label: 'Slug',
+          widget: 'string',
+        },
+        {
+          name: 'description',
+          label: 'Description',
+          widget: 'text',
+          i18n: true,
+        },
+        {
+          name: 'date',
+          label: 'Date',
+          widget: 'datetime',
+          i18n: 'duplicate',
+        },
+      ],
+    },
+    {
+      name: 'i18n_playground_single_file',
+      label: 'i18n (Single File)',
+      i18n: {
+        structure: 'single_file',
+        locales: ['en', 'de', 'fr'],
+        defaultLocale: 'en',
+      },
+      folder: 'packages/core/dev-test/backends/proxy/_i18n_playground_single_file',
+      identifier_field: 'slug',
+      create: true,
+      fields: [
+        {
+          name: 'slug',
+          label: 'Slug',
+          widget: 'string',
+        },
+        {
+          name: 'description',
+          label: 'Description',
+          widget: 'text',
+          i18n: true,
+        },
+      ],
+    },
   ],
 };
 
diff --git a/packages/core/src/components/entry-editor/EditorInterface.css b/packages/core/src/components/entry-editor/EditorInterface.css
index e0665949..be4db87e 100644
--- a/packages/core/src/components/entry-editor/EditorInterface.css
+++ b/packages/core/src/components/entry-editor/EditorInterface.css
@@ -14,19 +14,22 @@
 }
 
 & .CMS_Editor_i18n {
-  @apply flex
+  @apply hidden
     w-full
     overflow-y-auto
     h-main-mobile
     md:h-main;
+
+  &.CMS_Editor_i18n-active {
+    @apply flex;
+  }
 }
 
 & .CMS_Editor_mobile-i18n {
   @apply flex
     w-full
     overflow-y-auto
-    h-main-mobile
-    md:hidden;
+    h-main-mobile;
 }
 
 & .CMS_Editor_root {
diff --git a/packages/core/src/components/entry-editor/EditorInterface.tsx b/packages/core/src/components/entry-editor/EditorInterface.tsx
index 5a8596b4..bc1ae4ec 100644
--- a/packages/core/src/components/entry-editor/EditorInterface.tsx
+++ b/packages/core/src/components/entry-editor/EditorInterface.tsx
@@ -4,6 +4,7 @@ import { ScrollSyncPane } from 'react-scroll-sync';
 import { EDITOR_SIZE_COMPACT } from '@staticcms/core/constants/views';
 import { summaryFormatter } from '@staticcms/core/lib/formatters';
 import useBreadcrumbs from '@staticcms/core/lib/hooks/useBreadcrumbs';
+import { useIsSmallScreen } from '@staticcms/core/lib/hooks/useMediaQuery';
 import { getI18nInfo, getPreviewEntry, hasI18n } from '@staticcms/core/lib/i18n';
 import classNames from '@staticcms/core/lib/util/classNames.util';
 import {
@@ -34,6 +35,7 @@ export const classes = generateClassNames('Editor', [
   'root',
   'default',
   'i18n',
+  'i18n-active',
   'mobile-i18n',
   'split-view',
   'mobile-preview',
@@ -120,10 +122,12 @@ const EditorInterface = ({
 }: TranslatedProps<EditorInterfaceProps>) => {
   const config = useAppSelector(selectConfig);
 
+  const isSmallScreen = useIsSmallScreen();
+
   const { locales, defaultLocale } = useMemo(() => getI18nInfo(collection), [collection]) ?? {};
   const translatedLocales = useMemo(
-    () => locales?.filter(locale => locale !== defaultLocale) ?? [],
-    [locales, defaultLocale],
+    () => (isSmallScreen ? locales : locales?.filter(locale => locale !== defaultLocale)) ?? [],
+    [isSmallScreen, locales, defaultLocale],
   );
 
   const [previewActive, setPreviewActive] = useState(
@@ -140,6 +144,10 @@ const EditorInterface = ({
     (i18nActive ? translatedLocales?.[0] : defaultLocale) ?? 'en',
   );
 
+  useEffect(() => {
+    setSelectedLocale((i18nActive ? translatedLocales?.[0] : defaultLocale) ?? 'en');
+  }, [defaultLocale, i18nActive, translatedLocales]);
+
   useEffect(() => {
     loadScroll();
   }, [loadScroll]);
@@ -293,24 +301,44 @@ const EditorInterface = ({
   );
 
   const editorLocale = useMemo(
-    () => (
-      <div key={selectedLocale} className={classes.i18n}>
-        <EditorControlPane
-          collection={collection}
-          entry={entry}
-          fields={fields}
-          fieldsErrors={fieldsErrors}
-          locale={selectedLocale}
-          onLocaleChange={handleLocaleChange}
-          submitted={submitted}
-          canChangeLocale
-          context="i18nSplit"
-          hideBorder
-          t={t}
-        />
-      </div>
-    ),
-    [collection, entry, fields, fieldsErrors, handleLocaleChange, selectedLocale, submitted, t],
+    () =>
+      locales
+        ?.filter(l => l !== defaultLocale)
+        .map(locale => (
+          <div
+            key={locale}
+            className={classNames(
+              classes.i18n,
+              selectedLocale === locale && classes['i18n-active'],
+            )}
+          >
+            <EditorControlPane
+              collection={collection}
+              entry={entry}
+              fields={fields}
+              fieldsErrors={fieldsErrors}
+              locale={locale}
+              onLocaleChange={handleLocaleChange}
+              submitted={submitted}
+              canChangeLocale
+              context="i18nSplit"
+              hideBorder
+              t={t}
+            />
+          </div>
+        )),
+    [
+      collection,
+      defaultLocale,
+      entry,
+      fields,
+      fieldsErrors,
+      handleLocaleChange,
+      locales,
+      selectedLocale,
+      submitted,
+      t,
+    ],
   );
 
   const previewEntry = useMemo(
@@ -320,24 +348,35 @@ const EditorInterface = ({
   );
 
   const mobileLocaleEditor = useMemo(
-    () => (
-      <div key={selectedLocale} className={classes['mobile-i18n']}>
-        <EditorControlPane
-          collection={collection}
-          entry={entry}
-          fields={fields}
-          fieldsErrors={fieldsErrors}
-          locale={selectedLocale}
-          onLocaleChange={handleLocaleChange}
-          allowDefaultLocale
-          submitted={submitted}
-          canChangeLocale
-          hideBorder
-          t={t}
-        />
-      </div>
-    ),
-    [collection, entry, fields, fieldsErrors, handleLocaleChange, selectedLocale, submitted, t],
+    () =>
+      isSmallScreen ? (
+        <div key={selectedLocale} className={classes['mobile-i18n']}>
+          <EditorControlPane
+            collection={collection}
+            entry={entry}
+            fields={fields}
+            fieldsErrors={fieldsErrors}
+            locale={selectedLocale}
+            onLocaleChange={handleLocaleChange}
+            allowDefaultLocale
+            submitted={submitted}
+            canChangeLocale
+            hideBorder
+            t={t}
+          />
+        </div>
+      ) : null,
+    [
+      collection,
+      entry,
+      fields,
+      fieldsErrors,
+      handleLocaleChange,
+      isSmallScreen,
+      selectedLocale,
+      submitted,
+      t,
+    ],
   );
 
   const editorWithPreview = (
diff --git a/packages/core/src/components/entry-editor/editor-control-pane/EditorControlPane.tsx b/packages/core/src/components/entry-editor/editor-control-pane/EditorControlPane.tsx
index 06ee58af..bbd16d19 100644
--- a/packages/core/src/components/entry-editor/editor-control-pane/EditorControlPane.tsx
+++ b/packages/core/src/components/entry-editor/editor-control-pane/EditorControlPane.tsx
@@ -108,6 +108,7 @@ const EditorControlPane = ({
       {i18n?.locales && locale ? (
         <div className={classes.locale_dropdown_wrapper}>
           <LocaleDropdown
+            locale={locale}
             locales={i18n.locales}
             defaultLocale={i18n.defaultLocale}
             dropdownText={t('editor.editorControlPane.i18n.writingInLocale', {
diff --git a/packages/core/src/components/entry-editor/editor-control-pane/LocaleDropdown.css b/packages/core/src/components/entry-editor/editor-control-pane/LocaleDropdown.css
index 25ccba2a..07103840 100644
--- a/packages/core/src/components/entry-editor/editor-control-pane/LocaleDropdown.css
+++ b/packages/core/src/components/entry-editor/editor-control-pane/LocaleDropdown.css
@@ -1,4 +1,18 @@
 .CMS_LocaleDropdown_root {
+  &:not(.CMS_LocaleDropdown_no-edit) {
+    @apply flex
+      gap-2
+      items-center;
+  }
+}
+
+.CMS_LocaleDropdown_dropdown {
+}
+
+.CMS_LocaleDropdown_errors-icon {
+  @apply w-7
+    h-7
+    text-red-500;
 }
 
 .CMS_LocaleDropdown_no-edit {
diff --git a/packages/core/src/components/entry-editor/editor-control-pane/LocaleDropdown.tsx b/packages/core/src/components/entry-editor/editor-control-pane/LocaleDropdown.tsx
index 21430da6..af18733b 100644
--- a/packages/core/src/components/entry-editor/editor-control-pane/LocaleDropdown.tsx
+++ b/packages/core/src/components/entry-editor/editor-control-pane/LocaleDropdown.tsx
@@ -1,16 +1,31 @@
-import React from 'react';
+import Tooltip from '@mui/material/Tooltip';
+import { Error as ErrorIcon } from '@styled-icons/material/Error';
+import React, { useMemo } from 'react';
 
 import classNames from '@staticcms/core/lib/util/classNames.util';
 import { generateClassNames } from '@staticcms/core/lib/util/theming.util';
+import {
+  getEntryDataPath,
+  selectAllFieldErrors,
+} from '@staticcms/core/reducers/selectors/entryDraft';
+import { useAppSelector } from '@staticcms/core/store/hooks';
 import Menu from '../../common/menu/Menu';
 import MenuGroup from '../../common/menu/MenuGroup';
 import MenuItemButton from '../../common/menu/MenuItemButton';
 
+import type { ReactNode } from 'react';
+
 import './LocaleDropdown.css';
 
-export const classes = generateClassNames('LocaleDropdown', ['root', 'no-edit']);
+export const classes = generateClassNames('LocaleDropdown', [
+  'root',
+  'dropdown',
+  'errors-icon',
+  'no-edit',
+]);
 
 interface LocaleDropdownProps {
+  locale: string;
   locales: string[];
   defaultLocale: string;
   dropdownText: string;
@@ -20,6 +35,7 @@ interface LocaleDropdownProps {
 }
 
 const LocaleDropdown = ({
+  locale,
   locales,
   defaultLocale,
   dropdownText,
@@ -27,6 +43,49 @@ const LocaleDropdown = ({
   onLocaleChange,
   excludeLocales = [defaultLocale],
 }: LocaleDropdownProps) => {
+  const allFieldErrors = useAppSelector(selectAllFieldErrors);
+  const otherLocaleErrors = useMemo(() => {
+    return locales
+      .reduce((acc, l) => {
+        if (l === locale || excludeLocales.includes(l)) {
+          return acc;
+        }
+
+        const dataPath = getEntryDataPath(
+          {
+            currentLocale: l,
+            defaultLocale,
+            locales,
+          },
+          false,
+        ).join('.');
+        acc.push(
+          ...Object.keys(allFieldErrors).reduce((errors, key) => {
+            if (key.startsWith(dataPath)) {
+              errors.push(
+                ...allFieldErrors[key].filter(e => e.message).map(e => `${l}: ${e.message!}`),
+              );
+            }
+
+            return errors;
+          }, [] as string[]),
+        );
+        return acc;
+      }, [] as ReactNode[])
+      .map((e, index) => {
+        if (index === 0) {
+          return e;
+        }
+
+        return (
+          <>
+            <br />
+            {e}
+          </>
+        );
+      });
+  }, [allFieldErrors, defaultLocale, excludeLocales, locale, locales]);
+
   if (!canChangeLocale) {
     return (
       <div className={classNames(classes.root, 'CMS_Button_root', classes['no-edit'])}>
@@ -36,17 +95,24 @@ const LocaleDropdown = ({
   }
 
   return (
-    <Menu label={dropdownText} rootClassName={classes.root}>
-      <MenuGroup>
-        {locales
-          .filter(locale => !excludeLocales.includes(locale))
-          .map(locale => (
-            <MenuItemButton key={locale} onClick={() => onLocaleChange?.(locale)}>
-              {locale}
-            </MenuItemButton>
-          ))}
-      </MenuGroup>
-    </Menu>
+    <div className={classes.root}>
+      <Menu label={dropdownText} rootClassName={classes.dropdown}>
+        <MenuGroup>
+          {locales
+            .filter(locale => !excludeLocales.includes(locale))
+            .map(locale => (
+              <MenuItemButton key={locale} onClick={() => onLocaleChange?.(locale)}>
+                {locale}
+              </MenuItemButton>
+            ))}
+        </MenuGroup>
+      </Menu>
+      {otherLocaleErrors.length > 0 ? (
+        <Tooltip title={otherLocaleErrors}>
+          <ErrorIcon className={classes['errors-icon']} />
+        </Tooltip>
+      ) : null}
+    </div>
   );
 };
 
diff --git a/packages/core/src/lib/hooks/useMediaQuery.ts b/packages/core/src/lib/hooks/useMediaQuery.ts
new file mode 100644
index 00000000..b32460a5
--- /dev/null
+++ b/packages/core/src/lib/hooks/useMediaQuery.ts
@@ -0,0 +1,9 @@
+import { useMediaQuery } from '@mui/material';
+
+export function useIsMobile() {
+  return useMediaQuery('(max-width: 768px)');
+}
+
+export function useIsSmallScreen() {
+  return useMediaQuery('(max-width: 1024px)');
+}
diff --git a/packages/core/src/reducers/selectors/entryDraft.ts b/packages/core/src/reducers/selectors/entryDraft.ts
index 02f798aa..d2509fd6 100644
--- a/packages/core/src/reducers/selectors/entryDraft.ts
+++ b/packages/core/src/reducers/selectors/entryDraft.ts
@@ -17,6 +17,8 @@ export const selectFieldErrors =
     return state.entryDraft.fieldsErrors[fullPath] ?? [];
   };
 
+export const selectAllFieldErrors = (state: RootState) => state.entryDraft.fieldsErrors ?? {};
+
 export function selectEditingDraft(state: RootState) {
   return state.entryDraft.entry;
 }
diff --git a/packages/core/src/widgets/markdown/plate/components/buttons/common/ToolbarButton.tsx b/packages/core/src/widgets/markdown/plate/components/buttons/common/ToolbarButton.tsx
index 907c432f..ad1fe771 100644
--- a/packages/core/src/widgets/markdown/plate/components/buttons/common/ToolbarButton.tsx
+++ b/packages/core/src/widgets/markdown/plate/components/buttons/common/ToolbarButton.tsx
@@ -79,6 +79,7 @@ const ToolbarButton: FC<ToolbarButtonProps> = ({
     <Button
       key="button"
       aria-label={label ?? tooltip}
+      title={label ?? tooltip}
       variant="text"
       data-testid={`toolbar-button-${label ?? tooltip}`.replace(' ', '-').toLowerCase()}
       onClick={handleOnClick}