A race condition happens when multiple processes try to interact with the same files or folders at the same time. On Files.com, this occurs when multiple Syncs act on the same source or destination location, or when Automations or Remote Mounts target the same location being used by a Sync.

When these operations run at overlapping times, the order in which they start or finish is not predictable. The result is missing files, failed transfers, and partial operations.

Do not configure multiple workflows that use the same location unless you are certain they will not interfere with one another. This includes using the same folder or mount path in more than one Automation, Sync, or Mount-related process. These overlaps cause problems that are difficult to trace and troubleshoot.

For example, when an Automation and a Sync both act on the same files at the same time, one of them is likely to fail. The risk is higher when either is set to delete or move files after copying. One job may try to copy a file that another has already deleted, or two jobs may try to delete the same file, producing unpredictable behavior or log errors.

Files on remote servers may also be in use by another user or process on that system. Syncing files while they are in use on the remote server causes incomplete copies, failed moves, and file corruption.

Race conditions are not always obvious. Sometimes they show up in logs as errors like "not found" or "destination already exists." Other times they cause a job to skip files with no visible warning.

Avoiding Race Conditions with Sync

Do not set up multiple Syncs to use the same folder.

Do not use the same folder in both an Automation and a Sync, especially when either one deletes or moves files.

When possible, combine actions into a single Sync or Automation so everything happens in a predictable order.

Use unique Include and Exclude pattern matching in each Sync so the targets do not overlap.