To resolve this issue, follow these steps:

1. Check the version of your Trend Micro SafeSync program. Do the following:
   1. Right-click the Trend Micro SafeSync icon in your system tray, and then select Configure or Settings.
   2. Click the Updates or About tab.
2. Look for the Compile/Installed Version, and then do the step that applies.

   If the version is 5.0 or lower:

   1. Go to Start > Control Panel > Add or Remove Programs or Uninstall a program.
   2. Select Trend Micro SafeSync from the list, and then click Uninstall or Remove.
   3. Download the latest installer from the Trend Micro website, and then install your program.

   If the version is 5.1 or higher:

   This means that you already have the latest version installed. Proceed to the next step.

3. Verify the file extension of the locked file.
   Note: Below are the file extensions of common documents and their corresponding program that needs to be closed before synchronization:
   • .TXT - notepad
   • .DOC / .DOCX - Microsoft Word
   • .XLS / .XLSX - Microsoft Excel
   • .PPT / .PPTX - Microsoft Powerpoint
   • .PDF - Adobe Reader
4. Make sure that their corresponding programs are closed.
5. Try synchronizing the file again.
6. If the sychronization still fails, check and end all processes and programs that are running the files using the Task Manager:
   1. Press CTRL+ALT+DELETE.
   2. Click Task Manager.
   3. Click the Processes tab.
   4. Select the process that may use the file, and then click End Process.
7. Try synchronizing the file again.

If the issue still persists, generate debug logs for SafeSync and submit it to Trend Micro Technical Support for SafeSync for Consumer or SafeSync for Business.