Ask Ubuntu is a question and answer site for Ubuntu users and developers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I recently upgraded my 3G mobile broadband dongle to a newer model. Ubuntu recognizes it and I can connect/disconnect with no trouble. The problem comes when I try to safely remove the drive by right clicking its icon and choosing "Safely remove drive". When I do this I get a popup that displays the following

Unable to stop drive

Error detaching: helper exited with exit code 1: Detaching device /dev/sdc
USB device: /sys/devices/pci0000:00/0000:00:04.1/usb2/2-4)
SYNCHRONIZE CACHE: FAILED: No such file or directory
(Continuing despite SYNCHRONIZE CACHE failure.)
STOP UNIT: FAILED: No such file or directory

I don't really know what to do from here so I generally shutdown then remove the dongle as I do not want to damage it. Is this a common problem? Am I safe to just pull the dongle out after this message. The message is not particularly informative so I am not sure how best to proceed. I never had this problem with the previous model. Any advice would be very much appreciated. The model is identified as HUAWEI TD CARD storage

share|improve this question
Why is your USB modem/dongle showing up as storage? (note /dev/sdc)? – izx Jul 18 '12 at 18:44
I have no idea. I did not do anything to install it, it just got recognized when I plugged it in and allowed me to connect – mathematician1975 Jul 18 '12 at 18:46
lots of USB wireless broadband adapters have internal storage. typically, the drivers and software needed to make it work are stored on it. i've also seen plenty of adapters that have microsd slots on them. – longneck Jul 18 '12 at 19:03
I posted this as these devices are pretty common and I was wondering if anyone else had this problem and hopefully a solution. – mathematician1975 Jul 18 '12 at 19:06
I don't know anything about these devices, but... is there something that uses it that can be closed first? Also, have you tried unmounting rather than safely removing it? – Marty Fried Jul 18 '12 at 19:29
up vote 3 down vote accepted

It tries to synchronize its cache after the device has already been removed. It is a known bug and safe to ignore.

share|improve this answer

If you don't have a micro SD card or other storage connected via this device then just remove the device. The file manager may just be confused and tries to sync to the read only memory part of the device, which of course will fail. Just handle this device like a mouse or other non storage USB peripherals. You don't try to safely remove them, because there isn't even an option for doing so.

Btw: No, 3G/LTE USB sticks are horrible, there are to much models out there, they look all the same and you don't know which one works and which does not and they look goofy, too. That's why they have to go away. Buy mobile hotspots instead.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.