Help Please: Cannot Set Directory Locks in Ubuntu

[Jerry]

I'm running Ubuntu 18.04 LTS on my laptop with Free File Sync 11.28 [donation edition].

I bought a new Samsung Galaxy Fold 3 phone and was transferring files to it today from my laptop using a USB 3 cable.

To my horror the phone decided to do an automatic update and restart in the middle of Free File Sync synchronizing files.

The synchronization was running fine before that interruption happened. After that, no matter how I restart both devices or even delete the new directory on the phone and re-copy over the whole directory to the phone, Free File Sync, in testing, won't work with the directory on the phone anymore. It complains of 'Cannot set directory locks for the following folders" and continues to end with the directory tree in the phone and "/sync.ffs_lock. ENOTSUP: Operation not supported [open]". Ignoring the error doesn't help the sync to work properly.

Fortunately copying files to and from the new phone does work in the file system manager. Just Free File Sync won't work anymore on this directory...

As I write this I notice that if I open a text file on the phone, through the laptop (over the usb cable connection), and change anything and try to re-save it, the text editor gives an error "Cannot handle ... in write mode".

I don't understand; I was able to copy a whole directory.

Maybe this isn't an FFS problem; I'm not sure now.

Does anyone know how to solve? Otherwise I'll have to call Samsung.
Thank you.

[Jerry]

I'm in touch with Samsung support. It's likely an issue with the phone and not Free File Sync. Sorry if this is therefore an inappropriate question to post here; if it must be deleted I understand.

[bgstack15]

Nope, that sounded like a good thing to bring up here, because other FreeFileSync users might run into the same problem as you. I'm glad you also asked Samsung.

[Jerry]

I've been doing a bit of learning that MTP seems to be what the laptop and phone are using to interface, and, from my reading, although MTP works find for file transferring it is touchy regarding direct file editing. This seems to be where my problem lies: through the laptop, over USB cable, I can copy files to/from the phone, but direct editing, which seems to include permission for FFSync to write its sync.ffs_lock file, are obstructed. The bizarre thing is that it was working fine before my phone interrupted the original FFS file transfer. Ubunt seems to have some memory of devices it connects with. Maybe something remains in the phone remembering this connection the wrong way, with some residual problem left over from the abruptly interrupted file sync earlier. I'm working on it...

[Jerry]

And direct file editing works fine from my laptop over USB with my old phone right now, so it's not the laptop USB drivers that are the problem. Something is impaired with the new phone (Samsung Galaxy Fold 3) USB. Diagnostics there show normal. Working on it...