Expected another server reply(15) : 550 can't access file.

[commis@globetrotter.net]

I setup a FTP backup which I admit is very big (approx 25 GB), everything work fine except for 1 file. I run the backup every night and every night this file does not get saved and I get the following message. Expected another server reply(15) : 550 can't access file.
I have tried many things: renaming the file, changing the folder source and destination, creating a backup job specifically for that file, and also trying different times of day, but I always get the same error.
Here are details of the setup: both computers are running Windows XP Pro, I am using the latest Filezilla server version 0.9.31, the file is of type .zip,

[Tim Kosse]

Please attach some transfer logs.

[Tim Kosse]

This happens if the file is opened by some other program or if the account the service runs under (SYSTEM) does not have permissions to access the file.

[commis@globetrotter.net]

I can assure you that the file is not being used. the computer is a dedicated FTP server and is not used by anyone else or any other software. Why would it always be that file out of 40000 files and why every night.

[Tim Kosse]

Always the same file? Certainly not a problem with FileZilla Server, it's filename agnostic, it treats all files the same way, regardless of filename.

Check your filesystem for errors, uninstall all other third party programs.