When the same file is modified locally on a device and simultaneously in the cloud (e.g., via a web app or another device), a sync conflict occurs. Cloud sync services constantly track file versions. If changes happen in both locations before synchronization completes, the service detects differing versions and cannot automatically merge them into a single, coherent file. This differs from offline edits synchronized later without conflicts, where the latest change usually wins.

For example, editing a Word document saved to OneDrive locally while a colleague edits it through Office Online creates a conflict. Similarly, updating Python code on your laptop while pushing changes to the same Git repository branch from a cloud IDE triggers a merge conflict. These scenarios are common in collaborative platforms like Google Drive, Dropbox, GitHub, and SharePoint.

The main advantage is flexible access across devices, supporting remote work. A key limitation is potential data loss or overwrites if conflicts aren't resolved manually—typically by creating duplicate conflict files or prompting users to choose which version to keep. Best practice involves regularly syncing devices and communicating with collaborators to minimize risks. Future developments focus on smarter auto-merge for specific file types.