diff --git a/core/src/main/java/ch/cyberduck/core/shared/AbstractSchedulerFeature.java b/core/src/main/java/ch/cyberduck/core/shared/AbstractSchedulerFeature.java
index e74571ad5a7..d997e4a79b6 100644
--- a/core/src/main/java/ch/cyberduck/core/shared/AbstractSchedulerFeature.java
+++ b/core/src/main/java/ch/cyberduck/core/shared/AbstractSchedulerFeature.java
@@ -43,11 +43,38 @@ public AbstractSchedulerFeature(final long period) {
 
     @Override
     public Void repeat(final SessionPool pool, final PasswordCallback callback) {
-        scheduler.repeat(() -> {
+        scheduler.repeat(new PoolOperator(pool, callback), period, TimeUnit.MILLISECONDS);
+        return null;
+    }
+
+    public Void single(final Session<?> session, final PasswordCallback callback, final Path file) {
+        scheduler.schedule(new SessionOperator(session, callback, file), 0L, TimeUnit.MILLISECONDS);
+        return null;
+    }
+
+    protected abstract R operate(Session<?> session, PasswordCallback callback, Path file) throws BackgroundException;
+
+    @Override
+    public void shutdown() {
+        log.debug("Shutting down scheduler thread pool");
+        scheduler.shutdown();
+    }
+
+    private class PoolOperator implements Runnable {
+        private final SessionPool pool;
+        private final PasswordCallback callback;
+
+        public PoolOperator(final SessionPool pool, final PasswordCallback callback) {
+            this.pool = pool;
+            this.callback = callback;
+        }
+
+        @Override
+        public void run() {
             try {
                 final Session<?> session = pool.borrow(BackgroundActionState.running);
                 try {
-                    this.operate(session, callback, null);
+                    AbstractSchedulerFeature.this.operate(session, callback, null);
                 }
                 finally {
                     pool.release(session, null);
@@ -55,24 +82,41 @@ public Void repeat(final SessionPool pool, final PasswordCallback callback) {
             }
             catch(LoginFailureException | ConnectionCanceledException e) {
                 log.warn("Cancel processing scheduled task after failure {}", e.getMessage());
-                this.shutdown();
+                AbstractSchedulerFeature.this.shutdown();
             }
             catch(BackgroundException e) {
                 log.warn("Failure processing scheduled task. {}", e.getMessage(), e);
             }
             catch(Exception e) {
                 log.error("Failure processing scheduled task {}", e.getMessage(), e);
-                this.shutdown();
+                AbstractSchedulerFeature.this.shutdown();
             }
-        }, period, TimeUnit.MILLISECONDS);
-        return null;
+        }
     }
 
-    protected abstract R operate(Session<?> session, PasswordCallback callback, Path file) throws BackgroundException;
+    private class SessionOperator implements Runnable {
+        private final Session<?> session;
+        private final PasswordCallback callback;
+        private final Path file;
 
-    @Override
-    public void shutdown() {
-        log.debug("Shutting down scheduler thread pool");
-        scheduler.shutdown();
+        public SessionOperator(final Session<?> session, final PasswordCallback callback, final Path file) {
+            this.session = session;
+            this.callback = callback;
+            this.file = file;
+        }
+
+        @Override
+        public void run() {
+            try {
+                AbstractSchedulerFeature.this.operate(session, callback, file);
+            }
+            catch(BackgroundException e) {
+                log.warn("Failure processing scheduled task. {}", e.getMessage(), e);
+            }
+            catch(Exception e) {
+                log.error("Failure processing scheduled task {}", e.getMessage(), e);
+                AbstractSchedulerFeature.this.shutdown();
+            }
+        }
     }
 }
diff --git a/dracoon/src/main/java/ch/cyberduck/core/sds/SDSEncryptionBulkFeature.java b/dracoon/src/main/java/ch/cyberduck/core/sds/SDSEncryptionBulkFeature.java
index 47bd5f9e690..f1c309014db 100644
--- a/dracoon/src/main/java/ch/cyberduck/core/sds/SDSEncryptionBulkFeature.java
+++ b/dracoon/src/main/java/ch/cyberduck/core/sds/SDSEncryptionBulkFeature.java
@@ -99,7 +99,7 @@ public void post(final Transfer.Type type, final Map<TransferItem, TransferStatu
                                 final Path container = containerService.getContainer(file);
                                 if(rooms.get(container)) {
                                     log.debug("Run missing file keys for {}", file);
-                                    background.operate(session, callback, file);
+                                    background.single(session, callback, file);
                                 }
                             }
                         }