# How to debug "fatal: external diff died, stopping at ..."? 3 messages from 2023-01-09 to 2023-01-09. Participants: Sebastian Schuberth, Jeff Hostetler. Thread: https://gitlist.dev/t/59056 ## Sebastian Schuberth, 2023-01-09 13:35 Subject: How to debug "fatal: external diff died, stopping at ..."? Message-ID: URL: https://gitlist.dev/e/CAHGBnuOcNb0niPThM9gtmoJui%2Bbz1mmhKXjUn71P3Q53aM-HLA%40mail.gmail.com ``` Hi, similar to this [1] question on StackOverflow, ever since a distribution upgrade of my Fedora Linux box (KDE spin, now on release 37), my configured diff / merge tool (Beyond Compare 4) crashes with "fatal: external diff died, stopping at ..." after displaying the diff for the first file, for every operation I've tried so far (including resolving merge conflicts). I've also posted to the Beyond Compare forums [2], but the people from Scooter Software seem to be clueless as well. Would anyone have an idea how to debug this? PS: I also tried to use an X11 instead of a Wayland session with KDE / Plasma, but that did not help. [1]: https://askubuntu.com/questions/1437667/git-difftool-with-meld-broken-after-update-to-22-04-fatal-external-diff-died [2]: https://forum.scootersoftware.com/forum/beyond-compare-4-discussion/linux-aa/88824-bc4-as-a-git-merge-tool-says-fatal-external-diff-died -- Sebastian Schuberth ``` ## Jeff Hostetler, 2023-01-09 20:07 Subject: Re: How to debug "fatal: external diff died, stopping at ..."? Message-ID: <18a11fc5-ab72-a66a-6bef-7e460c762a9c@jeffhostetler.com> URL: https://gitlist.dev/e/18a11fc5-ab72-a66a-6bef-7e460c762a9c%40jeffhostetler.com In-Reply-To: ``` On 1/9/23 8:35 AM, Sebastian Schuberth wrote: > Hi, > > similar to this [1] question on StackOverflow, ever since a > distribution upgrade of my Fedora Linux box (KDE spin, now on release > 37), my configured diff / merge tool (Beyond Compare 4) crashes with > "fatal: external diff died, stopping at ..." after displaying the diff > for the first file, for every operation I've tried so far (including > resolving merge conflicts). I've also posted to the Beyond Compare > forums [2], but the people from Scooter Software seem to be clueless > as well. > > Would anyone have an idea how to debug this? > > PS: I also tried to use an X11 instead of a Wayland session with KDE / > Plasma, but that did not help. > > [1]: https://askubuntu.com/questions/1437667/git-difftool-with-meld-broken-after-update-to-22-04-fatal-external-diff-died > [2]: https://forum.scootersoftware.com/forum/beyond-compare-4-discussion/linux-aa/88824-bc4-as-a-git-merge-tool-says-fatal-external-diff-died > You might try turning on Trace2 in Git and see if there is any extra info there on the child processes. $ GIT_TRACE2_PERF=1 git difftool ... or $ export GIT_TRACE2_PERF=/absolute/path/to/logfile $ git difftool ... There you'll be able to see all of the "child_start" and "child_exit" events for each process that Git starts (at the "d1" level (and grandchildren at the "d2" level)). Maybe that'll reveal something. https://devblogs.microsoft.com/devops/a-deep-dive-into-git-performance-using-trace2/ Hope this helps, Jeff ``` ## Sebastian Schuberth, 2023-01-09 20:21 Subject: Re: How to debug "fatal: external diff died, stopping at ..."? Message-ID: URL: https://gitlist.dev/e/CAHGBnuMCBHME6jO9F%2BtU0sLHTTt%2BRtp3ktGyYi2GHQHab%2B56ZA%40mail.gmail.com In-Reply-To: <18a11fc5-ab72-a66a-6bef-7e460c762a9c@jeffhostetler.com> ``` Thanks Jeff, I meanwhile found out that the diff tool also crashes independently of its use with Git, and was able to isolate the problem a bit further using gdb. -- Sebastian Schuberth On Mon, Jan 9, 2023 at 9:07 PM Jeff Hostetler wrote: > > > > On 1/9/23 8:35 AM, Sebastian Schuberth wrote: > > Hi, > > > > similar to this [1] question on StackOverflow, ever since a > > distribution upgrade of my Fedora Linux box (KDE spin, now on release > > 37), my configured diff / merge tool (Beyond Compare 4) crashes with > > "fatal: external diff died, stopping at ..." after displaying the diff > > for the first file, for every operation I've tried so far (including > > resolving merge conflicts). I've also posted to the Beyond Compare > > forums [2], but the people from Scooter Software seem to be clueless > > as well. > > > > Would anyone have an idea how to debug this? > > > > PS: I also tried to use an X11 instead of a Wayland session with KDE / > > Plasma, but that did not help. > > > > [1]: https://askubuntu.com/questions/1437667/git-difftool-with-meld-broken-after-update-to-22-04-fatal-external-diff-died > > [2]: https://forum.scootersoftware.com/forum/beyond-compare-4-discussion/linux-aa/88824-bc4-as-a-git-merge-tool-says-fatal-external-diff-died > > > > You might try turning on Trace2 in Git and see if there is > any extra info there on the child processes. > > $ GIT_TRACE2_PERF=1 git difftool ... > > or > > $ export GIT_TRACE2_PERF=/absolute/path/to/logfile > $ git difftool ... > > There you'll be able to see all of the "child_start" and > "child_exit" events for each process that Git starts (at > the "d1" level (and grandchildren at the "d2" level)). > > Maybe that'll reveal something. > > https://devblogs.microsoft.com/devops/a-deep-dive-into-git-performance-using-trace2/ > > > Hope this helps, > Jeff ```