diff --git a/app/src/main/res/values-ca/strings.xml b/app/src/main/res/values-ca/strings.xml
index db902400..56a7ebc9 100644
--- a/app/src/main/res/values-ca/strings.xml
+++ b/app/src/main/res/values-ca/strings.xml
@@ -14,7 +14,6 @@
   <!--AddAccountActivity-->
   <string name="login_type_email">Entra amb una adreça de correu electrònic</string>
   <string name="login_type_url">Entra amb una URL i un nom d\'usuari</string>
-  <string name="login_auth_preemptive">Autentificació preferent (recomanat però incompatible amb l\'autentificació Digest)</string>
   <!--AccountSettingsActivity-->
   <!--collection management-->
   <!--ExceptionInfoFragment-->
diff --git a/app/src/main/res/values-cs/strings.xml b/app/src/main/res/values-cs/strings.xml
index d9e506a1..c8fd17c4 100644
--- a/app/src/main/res/values-cs/strings.xml
+++ b/app/src/main/res/values-cs/strings.xml
@@ -7,6 +7,9 @@
   <string name="please_wait">Chvíli strpení ...</string>
   <string name="send">Odeslat</string>
   <!--startup dialogs-->
+  <string name="startup_battery_optimization">Optimalizace využití baterie</string>
+  <string name="startup_battery_optimization_message">Android může po několika dnech vypnout/prodloužit interval synchronizování DAVdroid. Chcete-li tomuto zabránit, vypněte optimalizaci baterie.</string>
+  <string name="startup_battery_optimization_disable">Vypnout pro DAVdroid</string>
   <string name="startup_dont_show_again">Již nezobrazovat</string>
   <string name="startup_development_version">DAVdroid preview vydání</string>
   <string name="startup_development_version_message">Toto je vývojová verze aplikace DAVdroid. Mějte na paměti, že vše nemusí správně fungovat. Budeme rádi za konstruktivní zpětnou vazbu, která pomůže vylepšit DAVdroid.</string>
@@ -102,7 +105,6 @@
   <string name="login_user_name">Uživatelské jméno</string>
   <string name="login_user_name_required">Vyžadováno uživatelské jméno</string>
   <string name="login_base_url">Základní URL</string>
-  <string name="login_auth_preemptive">Preemptivní ověření (doporučeno, ale není kompatibilní s Digest ověřením)</string>
   <string name="login_login">Login</string>
   <string name="login_back">Zpět</string>
   <string name="login_create_account">Vytvořit účet</string>
@@ -123,9 +125,6 @@
   <string name="settings_password">Heslo</string>
   <string name="settings_password_summary">Aktualizovat heslo dle svého serveru.</string>
   <string name="settings_enter_password">Vložit své heslo:</string>
-  <string name="settings_preemptive">Preemptivní ověření</string>
-  <string name="settings_preemptive_on">Přihlašovací údaje jsou zasílány s každým požadavkem (doporučeno)</string>
-  <string name="settings_preemptive_off">Přihlašovací údaje jsou zasílány po vyžádání serverem</string>
   <string name="settings_sync">Synchronizace</string>
   <string name="settings_sync_interval_contacts">Interval synchronizace kontaktů</string>
   <string name="settings_sync_summary_manually">Pouze manuálně</string>
diff --git a/app/src/main/res/values-da/strings.xml b/app/src/main/res/values-da/strings.xml
index 5ff23881..8f8ec691 100644
--- a/app/src/main/res/values-da/strings.xml
+++ b/app/src/main/res/values-da/strings.xml
@@ -101,7 +101,6 @@
   <string name="login_user_name">Brugernavn</string>
   <string name="login_user_name_required">Brugernavn påkrævet</string>
   <string name="login_base_url">Basis-URL</string>
-  <string name="login_auth_preemptive">Forhåndsgodkendelse (preemptive authentication - anbefalet, men ikke kompatiblelt med Digest auth)</string>
   <string name="login_login">Login</string>
   <string name="login_back">Tilbage</string>
   <string name="login_create_account">Opret konto</string>
@@ -122,9 +121,6 @@
   <string name="settings_password">Adgangskode</string>
   <string name="settings_password_summary">Opdater adgangskoden, så den svarer til din server.</string>
   <string name="settings_enter_password">Indtast adgangskode:</string>
-  <string name="settings_preemptive">Forhåndsgodkendelse</string>
-  <string name="settings_preemptive_on">Loginoplysninger sendes ved hver anmodning (anbefalet)</string>
-  <string name="settings_preemptive_off">Loginoplysninger sendes efter server anmoder om dem</string>
   <string name="settings_sync">Synkronisering</string>
   <string name="settings_sync_interval_contacts">Synkroniseringsinterval for kontakter</string>
   <string name="settings_sync_summary_manually">Kun manuelt</string>
diff --git a/app/src/main/res/values-de/strings.xml b/app/src/main/res/values-de/strings.xml
index 2c0a9537..8fa79f4f 100644
--- a/app/src/main/res/values-de/strings.xml
+++ b/app/src/main/res/values-de/strings.xml
@@ -104,7 +104,6 @@
   <string name="login_user_name">Benutzername</string>
   <string name="login_user_name_required">Benutzername wird benötigt</string>
   <string name="login_base_url">Basis-URL</string>
-  <string name="login_auth_preemptive">Präemptive Authentifizierung (empfohlen, aber nicht kompatibel mit Digest-Auth.)</string>
   <string name="login_login">Anmelden</string>
   <string name="login_back">Zurück</string>
   <string name="login_create_account">Konto anlegen</string>
@@ -125,9 +124,6 @@
   <string name="settings_password">Passwort</string>
   <string name="settings_password_summary">Aktualisieren Sie Ihr Passwort gemäß den Server-Einstellungen.</string>
   <string name="settings_enter_password">Passwort eingeben:</string>
-  <string name="settings_preemptive">Präemptive Authentifizierung</string>
-  <string name="settings_preemptive_on">Anmeldeinformationen werden bei jeder Anfrage gesendet (empfohlen)</string>
-  <string name="settings_preemptive_off">Anmeldeinformationen werden nur auf Anforderung gesendet</string>
   <string name="settings_sync">Synchronisierung</string>
   <string name="settings_sync_interval_contacts">Häufigkeit der Kontakte-Synchronisierung</string>
   <string name="settings_sync_summary_manually">Nur manuell</string>
diff --git a/app/src/main/res/values-es/strings.xml b/app/src/main/res/values-es/strings.xml
index 62f26771..0c494da5 100644
--- a/app/src/main/res/values-es/strings.xml
+++ b/app/src/main/res/values-es/strings.xml
@@ -101,7 +101,6 @@
   <string name="login_user_name">Nombre de usuario</string>
   <string name="login_user_name_required">Nombre de usuario requerido</string>
   <string name="login_base_url">URL base</string>
-  <string name="login_auth_preemptive">Autenticación preferente (recomendado, pero incompatible con Digest auth)</string>
   <string name="login_login">Registrar</string>
   <string name="login_back">Volver</string>
   <string name="login_create_account">Crear cuenta</string>
@@ -121,9 +120,6 @@
   <string name="settings_password">Contraseña</string>
   <string name="settings_password_summary">Actualiza la contraseña de acuerdo a tu servidor.</string>
   <string name="settings_enter_password">Introduce tu contraseña:</string>
-  <string name="settings_preemptive">Autenticación preferente</string>
-  <string name="settings_preemptive_on">Las credenciales se envían en cada petición (recomendado)</string>
-  <string name="settings_preemptive_off">Las credenciales se envían después de que el servidor las pida</string>
   <string name="settings_sync">Sincronización</string>
   <string name="settings_sync_interval_contacts">Intervalo de sincronización de contactos</string>
   <string name="settings_sync_summary_manually">Solo manualmente</string>
diff --git a/app/src/main/res/values-fr/strings.xml b/app/src/main/res/values-fr/strings.xml
index beb42cf0..1900bd76 100644
--- a/app/src/main/res/values-fr/strings.xml
+++ b/app/src/main/res/values-fr/strings.xml
@@ -100,7 +100,6 @@
   <string name="login_user_name">Nom d\'utilisateur</string>
   <string name="login_user_name_required">Nom d\'utilisateur requis</string>
   <string name="login_base_url">URL de base</string>
-  <string name="login_auth_preemptive">Authentification préventive (recommandé, mais incompatible avec l\'authentification Digest)</string>
   <string name="login_login">Se connecter</string>
   <string name="login_back">Retour</string>
   <string name="login_create_account">Créer un compte</string>
@@ -120,9 +119,6 @@
   <string name="settings_password">Mot de passe</string>
   <string name="settings_password_summary">Mettre à jour le mot de passe </string>
   <string name="settings_enter_password">Saisissez votre mot de passe :</string>
-  <string name="settings_preemptive">Authentification préventive</string>
-  <string name="settings_preemptive_on">Le nom d\'utilisateur et le mot de passe sont envoyés avec chaque requête (recommandé)</string>
-  <string name="settings_preemptive_off">Le nom d\'utilisateur et le mot de passe sont envoyés à la demande du serveur.</string>
   <string name="settings_sync">Synchronisation</string>
   <string name="settings_sync_interval_contacts">Interval de synchronisation des carnets d\'adresses</string>
   <string name="settings_sync_summary_manually">Manuellement</string>
diff --git a/app/src/main/res/values-hu/strings.xml b/app/src/main/res/values-hu/strings.xml
index 263f0103..ed79787e 100644
--- a/app/src/main/res/values-hu/strings.xml
+++ b/app/src/main/res/values-hu/strings.xml
@@ -7,6 +7,9 @@
   <string name="please_wait">Kérjük, várjon ...</string>
   <string name="send">Küldés</string>
   <!--startup dialogs-->
+  <string name="startup_battery_optimization">Akkumulátoroptimalizálás </string>
+  <string name="startup_battery_optimization_message">Az operációs rendszer a DAVdroid szinkronizálást pár nap után leállíthatja vagy visszafoghatja.  Ennek elkerülésére kapcsolja ki az akkumulátoroptimalizálást.</string>
+  <string name="startup_battery_optimization_disable">Kikapcsolás a DAVdroid kapcsán</string>
   <string name="startup_dont_show_again">Ne jelenjen meg többet</string>
   <string name="startup_development_version">DAVdroid előzetes kiadás</string>
   <string name="startup_development_version_message">Ez a DAVdroid egy fejlesztői verziója.  Elképzelhető, hogy nem minden működik úgy, ahogyan kellene.  Ha így lenne, kérjük küldjön a tapasztaltakról visszajelzést.</string>
@@ -101,7 +104,6 @@
   <string name="login_user_name">Felhasználónév</string>
   <string name="login_user_name_required">A felhasználónév megadása feltétlenül szükséges</string>
   <string name="login_base_url">URL-törzs</string>
-  <string name="login_auth_preemptive">Preemptív authentikáció (ajánlott, de Digest authentikációval nem működik)</string>
   <string name="login_login">Bejelentkezés</string>
   <string name="login_back">Vissza</string>
   <string name="login_create_account">Fiók létrehozása</string>
@@ -122,9 +124,6 @@
   <string name="settings_password">Jelszó</string>
   <string name="settings_password_summary">Adja meg a szerveren érvényes új jelszót.</string>
   <string name="settings_enter_password">Adja meg a jelszót:</string>
-  <string name="settings_preemptive">Preemptív authentikáció</string>
-  <string name="settings_preemptive_on">A hitelesítő adatok elküldése minden kérésnél (ajánlott)</string>
-  <string name="settings_preemptive_off">A hitelesítő adatok elküldése, csak ha a szerver azt igényli</string>
   <string name="settings_sync">Szinkronizálás</string>
   <string name="settings_sync_interval_contacts">Névjegyszinkronizálás sűrűsége</string>
   <string name="settings_sync_summary_manually">Manuális</string>
@@ -161,6 +160,10 @@
   <string name="settings_sync_wifi_only_ssid_message">Adja meg a WIFI hálózat nevét (SSID) a szinkronizálás egy hálózatra való korlátozához, vagy hagyja üresen, ha nem akar ilyen szűkítést.</string>
   <string name="settings_carddav">CardDAV</string>
   <string name="settings_contact_group_method">A csoportok kezelésének módja</string>
+  <string-array name="settings_contact_group_method_values">
+    <item>GROUP_VCARDS</item>
+    <item>CATEGORIES</item>
+  </string-array>
   <string-array name="settings_contact_group_method_entries">
     <item>Minden csoport egy különálló VCard</item>
     <item>A csoportok a kapcsolatonkéni kategóriák</item>
diff --git a/app/src/main/res/values-ja/strings.xml b/app/src/main/res/values-ja/strings.xml
index 62e57779..40974422 100644
--- a/app/src/main/res/values-ja/strings.xml
+++ b/app/src/main/res/values-ja/strings.xml
@@ -7,6 +7,9 @@
   <string name="please_wait">しばらくお待ちください …</string>
   <string name="send">送信</string>
   <!--startup dialogs-->
+  <string name="startup_battery_optimization">バッテリー最適化</string>
+  <string name="startup_battery_optimization_message">Android は数日後に DAVdroid の同期を無効にする/減らすことがあります。これを防止するには、バッテリー最適化をオフにしてください。</string>
+  <string name="startup_battery_optimization_disable">DAVdroid 用にオフにする</string>
   <string name="startup_dont_show_again">次回から表示しない</string>
   <string name="startup_development_version">DAVdroid プレビュー リリース</string>
   <string name="startup_development_version_message">これは DAVdroid の開発版です。期待した通りに動作しない可能性があることにご注意ください。私たちが DAVdroid を改善するために、建設的なフィードバックをお願いします。</string>
@@ -100,7 +103,6 @@
   <string name="login_user_name">ユーザー名</string>
   <string name="login_user_name_required">ユーザー名が必要です</string>
   <string name="login_base_url">ベース URL</string>
-  <string name="login_auth_preemptive">プリエンプティブ認証 (推奨ですが、ダイジェスト認証と互換性がありません)</string>
   <string name="login_login">ログイン</string>
   <string name="login_back">戻る</string>
   <string name="login_create_account">アカウントを作成</string>
@@ -121,9 +123,6 @@
   <string name="settings_password">パスワード</string>
   <string name="settings_password_summary">ご利用のサーバーに従ってパスワードを更新します。</string>
   <string name="settings_enter_password">パスワードを入力:</string>
-  <string name="settings_preemptive">プリエンプティブ認証</string>
-  <string name="settings_preemptive_on">すべてのリクエストで資格情報を送信します (推奨)</string>
-  <string name="settings_preemptive_off">サーバーが要求した後、資格情報を送信します</string>
   <string name="settings_sync">同期</string>
   <string name="settings_sync_interval_contacts">連絡先同期間隔</string>
   <string name="settings_sync_summary_manually">手動のみ</string>
diff --git a/app/src/main/res/values-nl/strings.xml b/app/src/main/res/values-nl/strings.xml
index 0946e15a..b52353e2 100644
--- a/app/src/main/res/values-nl/strings.xml
+++ b/app/src/main/res/values-nl/strings.xml
@@ -101,7 +101,6 @@
   <string name="login_user_name">Gebruikersnaam</string>
   <string name="login_user_name_required">Gebruikersnaam vereist</string>
   <string name="login_base_url">Basis URL</string>
-  <string name="login_auth_preemptive">Preëmptieve authenticatie (aanbevolen, maar werkt niet met Digest-auth)</string>
   <string name="login_login">Login</string>
   <string name="login_back">Terug</string>
   <string name="login_create_account">Maak een account</string>
@@ -122,9 +121,6 @@
   <string name="settings_password">Wachtwoord</string>
   <string name="settings_password_summary">Gebruik het zelfde wachtwoord als op de server.</string>
   <string name="settings_enter_password">Wachtwoord invoeren:</string>
-  <string name="settings_preemptive">Preëmptieve authenticatie</string>
-  <string name="settings_preemptive_on">Credentials worden met elk verzoek verzonden (aanbevolen)</string>
-  <string name="settings_preemptive_off">Credentials worden alleen op aanvraag verzonden</string>
   <string name="settings_sync">Synchronisatie</string>
   <string name="settings_sync_interval_contacts">Contacten verversen</string>
   <string name="settings_sync_summary_manually">Alleen handmatig</string>
@@ -162,7 +158,7 @@
   <string name="settings_carddav">CardDAV</string>
   <string name="settings_contact_group_method">Contact groep methode</string>
   <string-array name="settings_contact_group_method_values">
-    <item>GROEP_VCARDS</item>
+    <item>GROUP_VCARDS</item>
     <item>CATEGORIES</item>
   </string-array>
   <string-array name="settings_contact_group_method_entries">
diff --git a/app/src/main/res/values-pl/strings.xml b/app/src/main/res/values-pl/strings.xml
index b0d1dd5e..485b02e2 100644
--- a/app/src/main/res/values-pl/strings.xml
+++ b/app/src/main/res/values-pl/strings.xml
@@ -82,7 +82,6 @@ Interfejs użytkownika</string>
   <string name="login_user_name">Nazwa użytkownika</string>
   <string name="login_user_name_required">Wymagana nazwa użtkonika</string>
   <string name="login_base_url">Podstawowy URL</string>
-  <string name="login_auth_preemptive">Autoryzacja prewencyjna (zalecana, ale niezgodna z autoryzacją Digest)</string>
   <string name="login_login">Zaloguj</string>
   <string name="login_back">Wróć</string>
   <string name="login_create_account">Stwórz konto</string>
@@ -101,9 +100,6 @@ Interfejs użytkownika</string>
   <string name="settings_password">Hasło</string>
   <string name="settings_password_summary">Zaktualizuj hasło zgodnie z serwerem.</string>
   <string name="settings_enter_password">Wpisz hasło:</string>
-  <string name="settings_preemptive">Autoryzacja prewencyjna</string>
-  <string name="settings_preemptive_on">Listy uwierzytelniające są wysyłane przy każdym zapytaniu (zalecane)</string>
-  <string name="settings_preemptive_off">Listy uwierzytelniające są wysyłane po zapytaniu serwera o nie</string>
   <string name="settings_sync">Synchronizacja</string>
   <string name="settings_sync_interval_contacts">Okres synchronizacji kontktów</string>
   <string name="settings_sync_summary_manually">Tylko ręcznie</string>
diff --git a/app/src/main/res/values-pt-rBR/strings.xml b/app/src/main/res/values-pt-rBR/strings.xml
index 688bdb72..8781d544 100644
--- a/app/src/main/res/values-pt-rBR/strings.xml
+++ b/app/src/main/res/values-pt-rBR/strings.xml
@@ -104,7 +104,6 @@
   <string name="login_user_name">Usuário</string>
   <string name="login_user_name_required">É necessário um nome de usuário</string>
   <string name="login_base_url">URL base</string>
-  <string name="login_auth_preemptive">Autenticação preferencial (recomendado, mas incompatível com autenticação Digest)</string>
   <string name="login_login">Autenticar</string>
   <string name="login_back">Voltar</string>
   <string name="login_create_account">Criar conta</string>
@@ -125,9 +124,6 @@
   <string name="settings_password">Senha</string>
   <string name="settings_password_summary">Atualize a senha de acordo com seu servidor</string>
   <string name="settings_enter_password">Digite sua senha:</string>
-  <string name="settings_preemptive">Autenticação preferencial</string>
-  <string name="settings_preemptive_on">Credenciais enviadas a cada requisição (recomendado)</string>
-  <string name="settings_preemptive_off">Credenciais enviadas após a requisição do servidor</string>
   <string name="settings_sync">Sincronização</string>
   <string name="settings_sync_interval_contacts">Intervalo sinc. de contatos</string>
   <string name="settings_sync_summary_manually">Apenas manualmente</string>
diff --git a/app/src/main/res/values-pt/strings.xml b/app/src/main/res/values-pt/strings.xml
index b05daefc..5cd88920 100644
--- a/app/src/main/res/values-pt/strings.xml
+++ b/app/src/main/res/values-pt/strings.xml
@@ -14,7 +14,6 @@
   <!--AddAccountActivity-->
   <string name="login_type_email">Login com seu enderço de email</string>
   <string name="login_type_url">Login com URL e nome do usuário</string>
-  <string name="login_auth_preemptive">Autenticação preferida (recomendado, mas incompatível com Digest)</string>
   <!--AccountSettingsActivity-->
   <string name="settings_authentication">Autenticação</string>
   <string name="settings_username">Nome de usuário</string>
@@ -22,9 +21,6 @@
   <string name="settings_password">Senha</string>
   <string name="settings_password_summary">Atualize sua denha de acordo com a do seu servidor.</string>
   <string name="settings_enter_password">Informe sua senha:</string>
-  <string name="settings_preemptive">Pre-emptive authentication</string>
-  <string name="settings_preemptive_on">Credenciais são enviadas com cadas requisição (recomendado)</string>
-  <string name="settings_preemptive_off">Credenciais são enviadas apos o servidor requisitar</string>
   <string name="settings_sync">Sincronização</string>
   <string name="settings_sync_interval_contacts">Intervalo de sincronização dos contatos</string>
   <string name="settings_sync_summary_manually">Manualmente apenas</string>
diff --git a/app/src/main/res/values-ru/strings.xml b/app/src/main/res/values-ru/strings.xml
index da79cf74..212d56be 100644
--- a/app/src/main/res/values-ru/strings.xml
+++ b/app/src/main/res/values-ru/strings.xml
@@ -15,7 +15,6 @@
   <!--AddAccountActivity-->
   <string name="login_type_email">Вход по адресу email</string>
   <string name="login_type_url">Вход через URL  и имя пользователя</string>
-  <string name="login_auth_preemptive">Упреждающая идентификация (рекомендовано, но несовместимо с Digest идентификацией)</string>
   <!--AccountSettingsActivity-->
   <string name="settings_authentication">Идентификация</string>
   <string name="settings_username">Имя</string>
@@ -23,9 +22,6 @@
   <string name="settings_password">Пароль</string>
   <string name="settings_password_summary">Обновить пароль в соответствии с вашим сервером.</string>
   <string name="settings_enter_password">Введите свой пароль:</string>
-  <string name="settings_preemptive">Упреждающая идентификация</string>
-  <string name="settings_preemptive_on">Учетные данные посылаются с каждым запросом (рекомендовано)</string>
-  <string name="settings_preemptive_off">Учетные данные посылаются после их запроса сервером</string>
   <string name="settings_sync">Синхронизация</string>
   <string name="settings_sync_interval_contacts">Интервал синхронизации контактов</string>
   <string name="settings_sync_summary_manually">Вручную</string>
diff --git a/app/src/main/res/values-sr/strings.xml b/app/src/main/res/values-sr/strings.xml
index 48ca7e32..8983cbac 100644
--- a/app/src/main/res/values-sr/strings.xml
+++ b/app/src/main/res/values-sr/strings.xml
@@ -105,7 +105,6 @@
   <string name="login_user_name">Корисничко име</string>
   <string name="login_user_name_required">Корисничко име је обавезно</string>
   <string name="login_base_url">Корени УРЛ</string>
-  <string name="login_auth_preemptive">Превентивна аутентификација (препоручено, али некомпатибилно са Дигест аутентификацијом)</string>
   <string name="login_login">Пријава</string>
   <string name="login_back">Назад</string>
   <string name="login_create_account">Направи налог</string>
@@ -126,9 +125,6 @@
   <string name="settings_password">Лозинка</string>
   <string name="settings_password_summary">Ажурирајте лозинку за ваш сервер.</string>
   <string name="settings_enter_password">Унесите лозинку:</string>
-  <string name="settings_preemptive">Превентивна аутентификација</string>
-  <string name="settings_preemptive_on">Слање акредитива са сваким захтевом (препоручено)</string>
-  <string name="settings_preemptive_off">Слање акредитива по захтеву сервера</string>
   <string name="settings_sync">Синхронизација</string>
   <string name="settings_sync_interval_contacts">Интервал синх. контаката</string>
   <string name="settings_sync_summary_manually">Само ручно</string>
diff --git a/app/src/main/res/values-tr-rTR/strings.xml b/app/src/main/res/values-tr-rTR/strings.xml
index 7cea0edf..2434afa5 100644
--- a/app/src/main/res/values-tr-rTR/strings.xml
+++ b/app/src/main/res/values-tr-rTR/strings.xml
@@ -101,7 +101,6 @@
   <string name="login_user_name">Kullanıcı adı</string>
   <string name="login_user_name_required">Kullanıcı adı zorunludur</string>
   <string name="login_base_url">Baz URL</string>
-  <string name="login_auth_preemptive">Önleyici doğrulama (tavsiye edilir, fakat Digest doğrulama ile uyumsuz)</string>
   <string name="login_login">Giriş</string>
   <string name="login_back">Geri</string>
   <string name="login_create_account">Hesap yarat</string>
@@ -121,9 +120,6 @@
   <string name="settings_password">Parola</string>
   <string name="settings_password_summary">Parolayı sunucunuza göre güncelleyin.</string>
   <string name="settings_enter_password">Parola girin:</string>
-  <string name="settings_preemptive">Önleyici doğrulama</string>
-  <string name="settings_preemptive_on">Giriş bilgileri her istek ile gönderilir (tavsiye edilir)</string>
-  <string name="settings_preemptive_off">Giriş bilgileri sunucu istedikten sonra gönderilir</string>
   <string name="settings_sync">Senkronizasyon</string>
   <string name="settings_sync_interval_contacts">Kişiler senk. aralığı</string>
   <string name="settings_sync_summary_manually">Sadece elle</string>
diff --git a/app/src/main/res/values-uk/strings.xml b/app/src/main/res/values-uk/strings.xml
index b82df3ac..6adbb9f4 100644
--- a/app/src/main/res/values-uk/strings.xml
+++ b/app/src/main/res/values-uk/strings.xml
@@ -14,7 +14,6 @@
   <!--AddAccountActivity-->
   <string name="login_type_email">Увійти за допомогою електронної пошти</string>
   <string name="login_type_url">Увійти за допомогою URL та імені користувача</string>
-  <string name="login_auth_preemptive">Випереджаюча автентифікація (рекомендовано, але несумісно із Digest auth)</string>
   <!--AccountSettingsActivity-->
   <string name="settings_authentication">Автентифікація</string>
   <string name="settings_username">Ім\'я користувача</string>
@@ -22,9 +21,6 @@
   <string name="settings_password">Пароль</string>
   <string name="settings_password_summary">Оновити пароль, згідно налаштувань Вашого сервера.</string>
   <string name="settings_enter_password">Введіть Ваш пароль:</string>
-  <string name="settings_preemptive">Випереджаюча автентифікація</string>
-  <string name="settings_preemptive_on">Дані автентифікації будуть надсилатися із кожним запитом (рекомендовано)</string>
-  <string name="settings_preemptive_off">Дані автентифікації будуть надіслані після відповідного запиту сервера</string>
   <string name="settings_sync">Синхронізація</string>
   <string name="settings_sync_interval_contacts">Інтервал синхронізації контактів</string>
   <string name="settings_sync_summary_manually">Лише вручну</string>
diff --git a/app/src/main/res/values-zh-rCN/strings.xml b/app/src/main/res/values-zh-rCN/strings.xml
index 45c92729..ff588b57 100644
--- a/app/src/main/res/values-zh-rCN/strings.xml
+++ b/app/src/main/res/values-zh-rCN/strings.xml
@@ -7,6 +7,9 @@
   <string name="please_wait">请稍等...</string>
   <string name="send">发送</string>
   <!--startup dialogs-->
+  <string name="startup_battery_optimization">电池优化</string>
+  <string name="startup_battery_optimization_message">系统可能会在几天后减少或停用 DAVdroid 同步。为了避免这一情况，请对 DAVdroid 忽略电池优化。</string>
+  <string name="startup_battery_optimization_disable">忽略电池优化</string>
   <string name="startup_dont_show_again">不再显示</string>
   <string name="startup_development_version">DAVdroid 预览版</string>
   <string name="startup_development_version_message">这是 DAVdroid 的开发版本，部分功能可能无法正常工作。请您提出建设性反馈，帮助我们完善 DAVdroid。</string>
@@ -100,7 +103,6 @@
   <string name="login_user_name">用户名</string>
   <string name="login_user_name_required">请输入用户名</string>
   <string name="login_base_url">根地址</string>
-  <string name="login_auth_preemptive">强制认证模式（推荐使用，但不兼容 Digest 认证方式）</string>
   <string name="login_login">登录</string>
   <string name="login_back">返回</string>
   <string name="login_create_account">创建账户</string>
@@ -121,9 +123,6 @@
   <string name="settings_password">密码</string>
   <string name="settings_password_summary">修改服务器密码</string>
   <string name="settings_enter_password">输入密码</string>
-  <string name="settings_preemptive">强制认证模式</string>
-  <string name="settings_preemptive_on">认证信息在每次请求中发送（推荐）</string>
-  <string name="settings_preemptive_off">认证信息在服务器要求后才发送</string>
   <string name="settings_sync">同步</string>
   <string name="settings_sync_interval_contacts">通讯录自动同步间隔</string>
   <string name="settings_sync_summary_manually">手动同步</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index dcffa1fa..cb47a0f9 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -123,7 +123,6 @@
     <string name="login_user_name">User name</string>
     <string name="login_user_name_required">User name required</string>
     <string name="login_base_url">Base URL</string>
-    <string name="login_auth_preemptive">Preemptive authentication (recommended, but incompatible with Digest auth)</string>
     <string name="login_login">Login</string>
     <string name="login_back">Back</string>
     <string name="login_create_account">Create account</string>
@@ -146,9 +145,6 @@
     <string name="settings_password">Password</string>
     <string name="settings_password_summary">Update the password according to your server.</string>
     <string name="settings_enter_password">Enter your password:</string>
-    <string name="settings_preemptive">Pre-emptive authentication</string>
-    <string name="settings_preemptive_on">Credentials are sent with every request (recommended)</string>
-    <string name="settings_preemptive_off">Credentials are sent after server requests them</string>
     <string name="settings_sync">Synchronization</string>
     <string name="settings_sync_interval_contacts">Contacts sync. interval</string>
     <string name="settings_sync_summary_manually">Only manually</string>