Synology NAS Error Code 64: How to Fix It
Medium 20-45 minutes Medium Severity
Verified June 2026
- Error Code
- 64
- Brand
- Synology
- Product Type
- nas
- Severity
- Medium
- DIY Difficulty
- Medium
- Estimated Fix Time
- 20-45 minutes
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Tools You'll Need
- Web browser (to access DSM interface)
- Administrator account credentials for DSM
- SSH client (e.g. PuTTY for Windows, Terminal for Mac/Linux) — optional for advanced step
- External storage drive or cloud destination for data backup
How to Fix Error Code 64
-
Check DSM Notifications and Log Center
-
Restart the Calendar Package
-
Verify That Required Dependent Services Are Running
-
Update DSM and the Calendar Package
Back up your NAS configuration and critical data before applying any DSM or package updates. Although updates rarely cause data loss, having a backup is essential good practice. -
Repair or Reinstall the Calendar Package
When uninstalling, choose 'Keep data' to preserve your calendar entries. Choosing 'Delete data' will permanently erase all calendar events stored on this NAS. -
Check Storage Volume Health
A degraded RAID volume is a serious condition. Do not add or remove drives without following Synology's official repair guidance, and back up all data immediately if a drive is failing. -
Reset DSM Calendar Service via SSH (Advanced)
Only enable SSH when actively using it and disable it immediately afterward. Running incorrect commands via SSH can damage your DSM installation. Proceed only if you are comfortable with command-line tools. -
Reboot the NAS
Ensure no critical file transfers or backup jobs are in progress before rebooting, as a reboot will interrupt active tasks.
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When to Call a Professional
Contact Synology support (support.synology.com) if Error Code 64 persists after completing all steps, if your storage volume shows a degraded or crashed status, if DSM itself fails to load or becomes inaccessible, or if you suspect a hardware failure such as a failing drive or memory issue. Synology's support team can provide remote diagnostic assistance and, if necessary, arrange a hardware replacement if your device is under warranty.Frequently Asked Questions
What does Synology Error Code 64 mean?
Synology Error Code 64 means the DSM Calendar service is currently unavailable on your NAS. This can happen because the Calendar package crashed, a dependent service stopped working, DSM software is outdated, or there is a storage volume issue affecting the service.
Will fixing Error Code 64 delete my calendar data?
Simply restarting or repairing the Calendar package will not delete your data. If you choose to uninstall and reinstall the Calendar package, make sure to select 'Keep data' during the uninstall process to preserve all your calendar events and shared calendars.
Why does my Synology Calendar keep going unavailable?
Recurring Calendar unavailability can be caused by an outdated DSM or Calendar package version, insufficient memory on the NAS causing services to be killed, a degraded storage volume, or a conflicting package. Keep DSM and all packages up to date and monitor your storage health regularly to prevent repeat occurrences.
Can I fix Synology Error Code 64 without SSH?
Yes. For most users, the issue can be resolved entirely through the DSM web interface by restarting, updating, or reinstalling the Calendar package. SSH is only needed as a last resort if the standard DSM controls cannot restart the service.
How do I back up my Synology Calendar data before troubleshooting?
Open the Calendar app in DSM, click the settings icon (gear icon) next to any calendar, and select 'Export Calendar' to download an ICS file. Repeat for each calendar you want to back up. Store these ICS files on an external drive or another location outside the NAS before proceeding with repairs.