Cerberus FTP is pleased to provide long file path support in all of its file system operations.

Following Windows 10 removal of the maximum of 260 characters for a file name and folder path limitation, this enhancement enables the ability to navigate through to a deeply nested directory and to handle zipping/unzipping directory structures in excess of 260 characters.

About Long File Path Support

Long file path support is an option in Windows 10 that allows files to be addressed at longer file names and a folder depth. We have under the hood improvements on how files and folders are addressed in our system, which address these issues but do not change how users interact with Cerberus FTP.  Instead, these improvements will work transparently to the original work flows. Many legacy products are restricted to a certain path length, and have bugs at expanded folder depths. With these changes to our server, Cerberus FTP is ready for other 3rd party products to follow our lead and handle their longer file paths.

HTTP/S Web Client Examples

Uploading A File At Path Limit:

Pre 12.7 release behavior:

A user has created a very long nested folder path, and attempted to upload a file at our folder name length limit:

Example with failed upload
Pre 12.7 HTTP/S Web Client interface behavior

This user encountered a 2048 character limit to the extended file name. As the user attempted to upload an image, Cerberus FTP truncated its filename during the file creation process.

New 12.7 release behavior:

Cerberus FTP web client now handles longer possible path names, even for a deeply nested folder.  This second image shows the resulting folder after uploading the image to the nested directory.  Here the file was uploaded correctly, with its full filename.

Example With Working Upload
New 12.7 HTTP/S Web Client interface behavior

Navigation Example:

In this example we present two contrasting displays of attempting to navigate deeply into the file system with the web client. In the first figure we have run up against the path length limit, and an attempt to access the ‘ag123456789’ folder fails halfway through navigation, truncating the path name.

Failed Navigation at Path Length Limit
Pre 12.7 HTTP/S Web Client navigation behavior

In the following figure, navigation continued down the folder tree properly to the final ‘last’ folder in the test cases.

Proper Navigation Past Original Path Length Limit
New 12.7 HTTP/S Web Client navigation behavior

Zip File Example:

When downloading a folder as a .ZIP file, a windows readable zip file is created, containing what the Cerberus FTP client could access with the original file system path and filename restrictions.  

Zipping A Folder
Zipping The Contents Of A Folder

With the new update, certain zip files may be created that windows explorer cannot read natively.

Windows Explorer Zip File Read Error
Windows Explorer Zip File Read Error

However, opening the resulting zip file with 7-zip, we can easily see the difference between the limits of the native windows and the newly expanded file processing.  Repeating the same file zipping operation with the extended file update creates an archive of all the folders instead of a smaller subset.  Here the 13th folder in the zip file tree expands past the 260 character filename length limit, as originally we were unable to zip that file into our archive.

Results Of Zipping A Folder, PreFix & Fixed
Results Of Zipping A Folder, PreFix & Fixed

These background changes to how the Cerberus FTP server addresses file paths are seamless to the user, and fix how we handle file paths that were originally too long.

Windows FTP Command Line Client Example

Changing Directories And Displaying Path (CD & PWD):

Pre 12.7 release behavior:

A user has created a very long nested folder path, and attempted to navigate directly to the folder via entering in the “cd” (change directory) command in the FTP client.  The path is changed in Cerberus FTP but we are unable to reply to a pwd (display current path) correctly causing a failure to send a full command and hanging the client.

Invalid Change Directory and Path
Invalid Change Directory and Path

Post 12.7 release behavior:

Cerberus FTP server now can reply with the correct longer path as a response to the “PWD” command in the midst of a long file path request.

Correctly Handled Change Directory and Path
Correctly Handled Change Directory and Path

Legacy Support Issues

Even with the Cerberus FTP server updates, there are limits on how completely other legacy products handle long file paths.  Here we run up against a limit on how long of a command the command line ftp client will process.  A full change directory command registering to the 524+ sub directory as seen will not be allowed on the command line.  Even as Cerberus FTP can handle a longer file path “CD” command, the native command line client will not send it.  Instead of changing to the 524th folder directly, the client stops accepting characters while typing out that folder name.  Relative navigation still works to change the working directory into 524, but we see here a place where the legacy software isn’t working to the new limits.

Command Line Navigation Failure
Command Line Navigation Failure, Too Long Of A Command


The enhanced long file path support  in Cerberus FTP Server 12.7.0 will help support troublesome cases in customer’s systems where extremely long file paths are used.  These changes will also help future proof your setup as more and more SFTP clients support extremely long file paths.  If you have any other questions or concerns, please contact us and give us feedback on your Cerberus FTP Server experience.