Synology Cloud Sync Not Syncing All Files – Solved Now!

Find Synology Cloud Sync not syncing all files but don’t know what to do? Read this article to get clear ideas.


By Lily Updated on January 8, 2024

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The error: Synology Cloud Sync not syncing all files

Synology Cloud Sync is an application provided by Synology to help users sync files between their Synology NAS and public cloud services. It supports various cloud services, including Amazon Drive, Dropbox, Google Cloud Storage, Microsoft Azure, and more. You are allowed to perform one-way or two-way sync between your NAS and other cloud services. You can also schedule the specific time and date to run automatic sync.

Powerful as Synology Cloud Sync seems to be, it fails to work sometimes. Some users find Synology Cloud Sync not syncing all files, only saying "Up to date". After trying to reinstall Cloud Sync and change DNS, there’s no difference. How frustrating it is!

Why and how to resolve Synology Cloud Sync stops syncing?

The Synology Cloud Sync not working problem can be caused by improper connection on Cloud Sync, low version of Cloud Sync, and the limitations imposed by cloud service providers. You can fix the issue with the following solutions:

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If you want an easier way to sync files between Synology NAS and a cloud drive, download the best free file sync tool here.

Solution 1: Reconnect Synology NAS and the cloud

1. On the Cloud Sync user interface, select the connection which has an issue from the left panel.

2. Under the Overview tab, click Manage. Then, choose Unlink to remove the connection of your Synology NAS and the cloud.

Remove Connection

3. Click on the “+” icon at the bottom-left corner to create the connection again. Cloud Sync should then start syncing the remaining folders and files.

Solution 2: Auto update Cloud Sync

Sometimes, the Synology Cloud Sync not syncing issue can result from low version of Cloud Sync. To fix it, please go to Package Center, click on the Cloud Sync package, and choose Auto-update from the drop-down menu.

Auto Update

Solution 3: Check limitations of a specific cloud

When you encounter the error of Synology Cloud Sync not syncing all files, you can also fix it by checking out the limitations of a specific cloud. Take Dropbox as an example. Files will not be synced by Cloud Sync if: (Learn more about cloud limitations >>)

  • The file name starts with .dropbox or .cache.

  • The file/folder name is/contains .dropbox.

  • The file has been uploaded for more than 48 hours.

To fix the problem of Synology Cloud Sync Dropbox not working, you can filter out certain file names in the following steps:

1. Select the cloud service that has an error from the connection list on the left.

2. Go to the Task list tab, select a sync task and click Edit.

Edit Task

3. Select the folders you want to sync under the Folder tab and prevent certain files from being synced under the File Filter tab.

File Filter

4. Click Apply to save your settings.

Easier way to sync files between Synology NAS and a cloud drive

If you have tried all the above solutions but still find Synology Cloud Sync not syncing all files, it is time to resort to another file sync tool. AOMEI Backupper Standard, the best free file sync software for Windows 11, 10, 8.1/8, 7, Vista and XP, comes to help.

  • Various sync sources and destinations: AOMEI Backupper Standard allows you to sync files between two folders, drives, or even two computers. You can also sync NAS to cloud, such as sync QNAP to OneDrive.

  • Schedule settings: You are allowed to create a daily/weekly/monthly sync task. It will automatically install a service to run missed sync at the next system startup.

  • Sync settings: You can set email notification to inform you of sync results and choose to sync deletions or not, etc.

Follow the guidance below to sync files between Synology NAS and a cloud drive:

Step 1. Download, install and run this free file sync tool.

Download Freeware Win 11/10/8.1/8/7/XP
Secure Download

Step 2. Click Sync and select Basic Sync. Basic Sync will perform one-way sync between Synology NAS and the cloud.

Basic Sync

Tip: If you want to perform two-way sync, real-time sync or mirror sync, AOMEI Backupper Professional can do you a favor.

Step 3. Edit the task name based on your needs. Then, click Add Folder > Share/NAS to add the Synology NAS path.

Add Folder

Step 4. Click Add Share or NAS Devices. In the next window, type the IP address of Synology NAS and click OK. Type username and password if it is needed.

Add Network Location

Step 5. After Synology NAS has been added, all the folders under it will be listed. Choose the folder you want to sync and click OK.

Step 6. Click the right edge of the second bar and choose Select a cloud drive.

Select a Cloud Drive

Step 7. Select a cloud from the list and click OK. If you don’t see your desired cloud in the list, then go back to Step 6 and manually navigate to the cloud local folder by clicking the second bar.

Select Cloud

Step 8. Confirm the source and destination directory and click Start Sync.

★ Bonus tip: backup files to AOMEI Cloud

As cloud storage is becoming more and more popular, AOMEI offers users its own cloud - AOMEI Cloud. You can backup files to AOMEI Cloud if you have an AOMEI account. You'll get 1TB free storage for 15 days after you sign up for an AOMEI account.



To resolve Synology Cloud Sync not syncing all files, you can try the solutions offered in this article. If you are disappointed at Synology Cloud Sync, you can turn to AOMEI Backupper. The sync process with AOMEI Backupper is easier, and it supports not only Synology NAS but also QNAP, WD My Cloud, and Seagate Personal Cloud, etc.

What’s more, AOMEI Backupper is powerful hard drive transfer software that can help you transfer OS and data from one hard drive to another. Why not try it now?

Lily · Editor
Lily Green joined AOMEI in 2018 and has since become a professional in the areas of data protection and data transfer. She is committed to helping users protect their precious computer data and troubleshoot Windows system errors. She consistently stays vigilant about the latest trends in technology, guaranteeing that the given information aligned with the ongoing advancements in the field.