When I try to format a USB flash drive, I get an error message.

[Schlaffie]

When I try to format a USB flash drive, I get an error message.
"This drive is in use. Another program or process is using the drive. Do you still want to format it?"
With "yes" it will be formatted.
In Windows Explorer, this message does not appear.
What can I do or is this a bug?

[Mathias (Author)]

I'm not able to recreate that..
But if you are showing the content of the device and there are lots of files a background process is running to get icons and such. And if you select to format the device before this is done I guess Windows see that it is in used.

[Schlaffie]

No, this also happens when the USB flash drive is empty and I want to format it.
Tested with 3 different USB flash drives.

[Schlaffie]

I have just tested.
I installed Multi Commander on another laptop Win10 64bit.
Windows Explorer - works without error message
Speedcommander trial version - works without error message
Multi Commander x64 - error message
Multi Commander x86 - error message

[Mathias (Author)]

Not sure what the problem is,
It is not an error.. It is a warning saying it is in used. but you continue and it gets unmounted  formated.. and then remounted.

[Schlaffie]

I have found the problem.
Let's say the USB flash drive is drive F.
If drive F is open in the window of Multi Commander and I want to "format" via the context menu comes the message.
I can't safely remove drive F then either.

If drive C is open in the Multi Commander window and I right click on drive F at the top of the drive list and choose "format" from the context menu then the error message does not come.
I can then safely remove the F drive.

So Windows always considers drive F as in use when it is open in Multi Commander window, although no file operations are performed.

[Mathias (Author)]

Yes that is because file notification is active on the filesystem, So MC gets notified and refresh the view if anything is changed on the drive.
But there is no exclusive lock.. Windows will allow the device to be unmounted anyway

[Schlaffie]

What can I do about it now?
It works with other file explorers too!
Only not with MC!

[Mathias (Author)]

I don't see it as it does not work.. You get a warning that something is using the device because of file notification.  But it does not prevent you from just clicking continue.
If you do not want to see a warning. then navigate away from the device before format

Windows can unsubcribe on file notification it self since it has full control of the shell. But MC is not build ontop of the shell. So MC does not know that the format tool have started.

[Schlaffie]

Thanks for the detailed answer!