Windows: 4 GiB file size limit on virtual drive

Sadly, Windows cannot handle files larger than 4 GiB via WebDAV. Since the virtual drive is currently based on WebDAV, no files larger than that can be encrypted using Windows Explorer.

That said, Cryptomator can easily handle much larger files if the vault is accessed using some better software, such as Cyberduck. Here is a guide on how to do that: Can I use alternative WebDAV clients?

We’re trying to work around this limitation by providing the virtual drive using some other technology than WebDAV in future versions. The progress is documented on GitHub

Update February 2022: The 4GiB limit only applies to WebDAV-mounted vaults on Windows. Instead of WebDAV, you can install two other virtual file system providers:

  • WinFSP the preferred solution in 2022
  • Dokany 1.x if you need custom mount points (note that 2.x is not supported)

To understand it correctly:
When using the desktop app cryptomator, the vault is mounted via WebDAV from the application. Thats why FAT is shown as the file system? And thats why no files larger than 4 GiB can be copied to the mounted drive?

Yes, only Windows shows WebDAV mounts as FAT file systems. Other WebDAV clients are capable of writing larger files.

Info for this Thread as well:

How about Mountain Duck?
Is it able to handle files larger than 4GB?

I’m working with Windows and I have mounted a Fileshare as Z:
There I have installed a safe that finally appears as Y:

Yes, Mountain duck instead of windows WebDAV should work as well. See linked post above:

does not work here, i tried to upload a 4.8 GB file and it stops at 2GB

it’s 2022 now.
I just try again using 1.6.5 and ctmt can now use webdav, winfs or dokany.

if i choose dokany, is it the 4GB file size limit is not there now?

btw, but the android one still use webdav right? thx.


I’m having the same issue. I can’t store 4gb > files it just fails.

What alternatives do I have to handle large files?

Cyberduck does the trick

After some more testing time both apps (Cyberduck and Mountain duck) are awkward at best and unusable at worst for me, obviously built for a different use case.
It’s really unfortunate that you cannot copy 4gb files on windows normally.

I guess I need to edit the original post, since there are two alternatives here: WinFSP and Dokany. Both work with virtually arbitrarily large files.

i am on win10 64bit,
i want to tell that unlike cppcryptfs that work well with dokany,
cryptomator works better with winfsp.

ctmt+dokany resulted in weird behaviours for me.
like ask to unlock while it 's already been unlocked.