How To Fix Windows Offline File Sync Error

When trying to sync offline files in Windows you may sometimes get an error “parameter is incorrect”.

Before I show you how to fix it, I'll tell you what's most probably gone wrong. This quote is a post I found in the digitalspy forum (see my sources) and explains it beautifully.
"The simplest explanation is that you've exceeded the maximum path and/or file lengths.
On Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters. 'Path' includes all the nested folder names, eg "C:\MyPrograms\Microsoft Office". 'File Names' include the extension."

Now here's a great way to identify which path or file is causing the problem.

1. Get the Path Scan app from here http://www.softpedia.com/get/System/File-Management/Path-Scan.shtml (This is an older version of Path Scanner but you need it because it works with UNC paths - i.e. paths that start with double-slash '\\' - whereas the newer version of the program on the official web site does not work with UNC paths, it only works with paths starting with a drive letter, e.g. c:\ and that's useless because the path length problem is all about the length of the full UNC path.)
2. Now go online and sync with your server so you can see the sync error "parameter is incorrect" again. 
3. Look at the error to check the path where the problem occurred.
4. Paste this path into Path Scanner and don't forget to add a wildcard, e.g. it must end with ‘\*’
• E.g. \\file-abc01.work.intern\home$\joeblow\*
5. In Port Scanner set the "Display files with more than" option to 261 char.
6. Then click Scan to locate the files for which the path is too long and do something about them.
• E.g. Back up the file and/or folder that is causing the problem somewhere else, then delete it from the original location and try to sync again.

Sources

http://www.digitalspy.co.uk/forums/showthread.php?t=744475

http://www.microsoft.com/windowsserver2003/techinfo/overview/dfsfaq.mspx#EPBAC