Why Does My FileSystemWatcher's OnChanged Event Fire Twice After Modifying a File?

Understanding Duplicate OnChanged Events in FileSystemWatcher

You're using FileSystemWatcher's OnChanged event to track file modifications, but notice the event fires twice when you change a file (like Version.txt), even with NotifyFilters.LastWrite specified.

Why This Happens

The FileSystemWatcher documentation explains that multiple events can be triggered by a single file operation. Text editors often write to disk in stages, resulting in multiple file system changes and thus multiple events.

Addressing the Issue

While filtering duplicate events manually is one approach, it's not always foolproof. The NotifyFilter property itself may not fully prevent this behavior in all scenarios. For more robust solutions, explore alternative techniques. Refer to this resource for advanced strategies:

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