Square bracket destination drive not recognized and shows "?:\[EXT_DRIVE]"

[Mosto]

Hello.

I have created an NTFS VeraCrypt partition on an external drive, then renamed it as "EXT_DRIVE" partition name.
Then I setup a FreeFileSync configuration to write to that drive by its partition name above for some root directories like "DVD", "Data", "Installers". Instead of using the partiton drive letter, I used "[EXT_DRIVE]" in square brackets to determine the destination backup partition.
Hence I have 3 destination backup directory entries like this in FreeFileSync:
[EXT_DRIVE]\DVD
[EXT_DRIVE]\Data
[EXT_DRIVE]\Installers

This works very well, no issue at all to backup all files.

However I setup exactly the same on another drive, also with VeraCrypt NTFS partition, and this fails this time.
The error is the following (immediately after starting to write to the backup drive):
Cannot find the following folders:
?:\[EXT_DRIVE]\DVD
?:\[EXT_DRIVE]\Data
?:\[EXT_DRIVE]\Installers
Cannot read the file attributes of "?:\[EXT_DRIVE]".

For any reason, FreeFileSync adds a question mark before the square brackets, and especially this sequence of characters: "?:\", before the square brackets destination name.

I really don't know what can cause this to happen, why on the second drive it does this whereas on the first drive it works perfectly. I tried to reformat completely the new drive and partition but it remains the same.

Please help.
Thank you.

[Zenju]

"?:\" means a volume with this name was not found. Generally it's best to not enter the volume name manually, but pick the name from the drop-down list instead: https://freefilesync.org/manual.php?topic=variable-drive-letters

[xCSxXenon]

"?:\" means a volume with this name was not found. Generally it's best to not enter the volume name manually, but pick the name from the drop-down list instead: https://freefilesync.org/manual.php?topic=variable-drive-letters

To clarify the process:
Use the drive letter in FFS to set up the sync. Once you have the driver letter of the location, the dropdown arrow can be clicked to show alternative syntaxes for the same location, one of which includes the square bracket notation

[Mosto]

Thank you for this link and info.

Interesting to know that "?:\" indicates that a volume of this name was not found.
In my opinion this is a bug of FreeFile Sync, because there is really a volume of this name I entered. I triple-checked this, and the volume is properly mounted and I can write to it properly.

I cannot really select another drop-down menu, because I am using the same FFS configuration file for all drives. They just need to be named "EXT_DRIVE" and I can backup on several disks. This worked very well up to now without a VeraCrypt disk (so with two different disk having the same name).

So there is something that makes that the volume is not properly recognized with this name, although the volume HAS this name.

Maybe you could provide me with the source file and function name that checks this so that I could try to look into it a bit more?

[Zenju]

Problem could be a typo of some kind. First select the volume by path, then open the drop down and see what FFS is offering.

[Mosto]

Thank you for the suggestion but this was not the issue.

So I investigated a bit more and found interesting things.
It is not related to a FreeFileSync issue, this is merely related to VeraCrypt or Windows or a combination of both.

What happens is that this situation occurs when we create a VeraCrypt volume, with a default name or no name, and then we rename it from the Windows Explorer with the "Rename" right-click option (or double-click on the name).
In this case, the VeraCrypt volume is properly displaying the volume name (EXT_DRIVE), and even if we reboot the computer.
However, when we type the DOS command "dir" on that partition, then it shows the previous name or no name!
It is a very strange situation and a bug, but not due to FreeFileSync, because the "dir" command shows the same issue.

SOLUTION
Hence the solution I found was to force renaming the volume from a command prompt with this command:
label X:EXT_DRIVE
Where X is the drive letter and "EXT_DRIVE" is the target volume name.

After this, the volume name is really changed, and now the backup works perfectly again!

Still thanks for your support.