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Troubleshooting FileSystemWatcher Components 

You may encounter the following situations while working with the FileSystemWatcher component:

If you are working with a FileSystemWatcher component on a Windows NT version 4.0 computer and trying to set its path to monitor file system activity on a different Windows NT version 4.0 computer, you will not be able to specify a UNC-based path value in the Path property to point to the computer in question. You can only set UNC-based values when working on Windows 2000 computers.

If you set your FileSystemWatcher component to reference a directory on a Windows 95 or Windows 98 computer, you will receive an error about an invalid directory path when the project runs. When using FileSystemWatcher , you cannot watch directories on computers running Windows 95 or Windows 98.

You may notice in certain situations that a single creation event generates multiple Created events that are handled by your component. For example, if you use a FileSystemWatcher component to monitor the creation of new files in a directory, and then test it by using Notepad to create a file, you may see two Created events generated even though only a single file was created. This is because Notepad performs multiple file system actions during the writing process. Notepad writes to the disk in batches that create the content of the file and then the file attributes. Other applications may perform in the same manner. Because FileSystemWatcher monitors the operating system activities, all events that these applications fire will be picked up.


Notepad may also cause other interesting event generations. For example, if you use the NotifyFilter to specify that you want to watch only for attribute changes, and then you write to a file in the directory you are watching using Notepad, you will raise an event . This is because Notepad updates the Archived attribute for the file during this operation.

Changing a file within a directory you are monitoring with a FileSystemWatcher component generates not only a Changed event on the file but also a similar event for the directory itself. This is because the directory maintains several types of information for each file it contains — the names and sizes of files, their modification dates, attributes, and so on. Whenever one of these attributes changes, a change is associated with the directory as well.