ubuntustudio-bugs team mailing list archive

[Peter Flynn <peter@xxxxxxxxxxx>]

On 09/07/18 17:27, SunBear wrote:
> I see the following  message from Shotwell 0.22.0 in Ubuntu 16.04
> every time a iPhone4s is plugged in to my computer usb:
> 
> Shotwell Unable to fetch previews from the camera: Could not claim
> the USB device (-53)
> 
> I have to click "Ok" to remove this message before I can access
> Shotwell. This warning has always appeared for a few years. Annoying.
> It will be great that this warning be removed.

You are very lucky that clicking OK enables you to proceed like that.

This is a well-known and pervasive bug which has remained unfixed for
many years, for some unknown reason.

"Could not claim the USB device (-53)" means that some other process (I
believe a driver of some kind) has already grabbed the device without
authorization, and will not let go of it.

This kind of usurpation is not really something we want in an operating
system. We need to get to the bottom of it, and delete the process which
is apparently jumping in where it is not wanted. I am guessing — because
I cannot find any concrete information — that it is a kernel driver
installed for some other, perfectly authentic, reason, which is doing
this as an unwanted side-effect, so the author may be completely unaware
that this is happening.

I have already recommended elsewhere that the correct interim solution
is for camera applications (in your case, Shotwell, but in fact almost
anything that needs access to the camera, even a plain file manager) to
be able (with sudo authentication) to kill the current claiming process,
break the lock, and give the application the access it needs.

Long term, it should be possible to identify to the user *what* process
has claimed the USB device uninvited, and allow the user to kill the
process permanantly (ie remove it from whatever autostart procedure it
was spawned from). Until that happens, camera software usage is largely
crippled.

///Peter

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https://bugs.launchpad.net/bugs/1400470

Title:
  cannot download photos using shotwell via usb

Status in shotwell package in Ubuntu:
  Fix Committed

Bug description:
  I get error message "Unable to fetch previews from the camera:
  Could not claim the USB device (-53)" when I try to connect my camera and download photos to the PC using Shotwell. I have also installed gThumb and still same message.

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