Creating isos of some DVDs fails with "Data could not be written"

Thanks for your report, could you get a brasero log? please run brasero as: brasero --debug --brasero-media-debug &> brasero-debug.txt ; perform the operation to reproduce the bug and attach that resulting log file to the report, thanks.

Checking session consistency (brasero_burn_check_session_consistency brasero-burn.c:1848)
BraseroDvdcss called brasero_job_get_action
BraseroDvdcss called brasero_job_get_action
BraseroDvdcss called brasero_job_get_current_track
BraseroDvdcss called brasero_job_set_output_size_for_current_track
BraseroDvdcss stopping
BraseroDvdcss called brasero_job_get_action
BraseroDvdcss called brasero_job_get_session_output_size
BraseroDvdcss output set (IMAGE) image = /media/Medium/out.iso toc = none
BraseroDvdcss called brasero_job_get_action
BraseroDvdcss called brasero_job_set_use_average_rate
BraseroDvdcss called brasero_job_set_current_action
BraseroDvdcss called brasero_job_get_current_track
BraseroDvdcss called brasero_job_set_current_action
BraseroDvdcss called brasero_job_get_fd_out
BraseroDvdcss called brasero_job_get_image_output
BraseroDvdcss called brasero_job_error
BraseroDvdcss finished with an error
BraseroDvdcss asked to stop because of an error
 error = 1
 message = "Data could not be written (Input/output error)"
BraseroDvdcss stopping
Session error : Data could not be written (Input/output error) (brasero_burn_record brasero-burn.c:2808)

I experienced the same bug, which terminates in the same way. Above is the log from my session.

Turns out there was corruption in the DVD I was trying to backup. A workaround for the corrupted DVD I was reading was to do the copying from the command line with a different tool.

To install the tool run...

sudo apt-get install gddrescue

...or install gddrescue through a graphical package manager like synaptic then use the following to copy the stream in a way which abandons the corrupted sectors, rather than allowing them to junk the copy. In the terminal unmount the drive and start the copy process like this...

umount /dev/sr0
ddrescue -d -n -b 2048 /dev/sr0 /home/cefn/out.iso /home/cefn/out.log

...where /dev/sr0 should be replaced with the raw path to your DVD device, and the other two paths are the disk image file and the log file respectively.

I got the raw path /dev/sr0 of my DVD device by running...

mount -l

...after the DVD had first automounted. It reported the line; /dev/sr0 on /media/cdrom0 type udf (ro,nosuid,nodev,utf8,user=cefn). Note it's the first path in this line about the cdrom drive which you should use.

Depending on your permissions you may need to prefix commands with the word sudo to elevate your privileges so you can access devices directly.

I thought this was really weird since I could view the DVD in VLC fine, but not copy it.

It seems that DVD players already know how to handle corrupted sectors, but copy programs typically do not. Copies made of corrupted disks, even if they appear to work as far as the menu, come out as junk when you try to play the part of the video which is stored with corrupted sectors, since the copy program produces a disk image with different kinds of error than the corrupted original, and so the player can't use the same tricks to skip over corrupted sectors.

Given the nature of this problem it would help if the error showed 'Data could not be read' rather than 'Data could not be written' since I spent a bunch of time checking my hard disks which were fine.

For the record the line
mount -l
Written above is lowercase "L". It was hard to tell with the font forced in there.

Also as an example of the drive, mine looked like:
/dev/sr0 on /media/TRUE_GRIT type udf ................