PCManFM & Nautilus crash immediately after opening

Started segfaulting again, but resolved spontaneously and showed the files on the third try, with not changes. I also have Caja and Nemo installed, and intend to try Nemo if it happens again.

This is annoyingly intermittent, in particular because there is a pattern of pcmanfm crashing after launch for 4-6 times in a row, then you attempt a fix and it appears to work after that. Could it be dependent on some uninitialised data? I can try a memtest.

Sometimes launching from gnome-terminal without any other changes stops the crash. I've also tried letting the window open and then choosing a shortcut from 'Places' and it stays open. So maybe it's related to a file in my home directory (I have some weird stuff there like tcpdumps). Note that current options are 'Show thumbnails of files' is not ticked, but 'Only show thumbnails for local files' is ticked - not that that combination makes much sense.

I also tried
  mkdir causing-pcmanfm-probs && find . -maxdepth 1 -type f -mtime -365 | grep -v '\./\.' | xargs -I{} mv {} causing-pcmanfm-probs/
and that seemed to allow pcmanfm to open - this time :)

I could try gdb on a dumped core to get some clues, but I always find it difficult to get one with Apport installed.

PS: comment 2 should read 'with no changes'.

A few more notes:

strace shows:
...
connect(11, {sa_family=AF_LOCAL, sun_path="/tmp/.pcmanfm-socket--0-cedric"}, 32) = 0
fcntl64(11, F_GETFL) = 0x2 (flags O_RDWR)
stat64(".", {st_mode=S_IFDIR|0755, st_size=20480, ...}) = 0
stat64("/home/cedric", {st_mode=S_IFDIR|0755, st_size=20480, ...}) = 0
fstat64(11, {st_mode=S_IFSOCK|0777, st_size=0, ...}) = 0
write(11, "/home/cedric\n0\n", 15) = 15
close(11) = 0
close(11) = -1 EBADF (Bad file descriptor)
exit_group(0) = ?
+++ exited with 0 +++

deleting this named socket also seems to allow pcmanfm to launch. Why does it try to close it twice?

Jan 20 10:53:29 PC-2 kernel: [ 2998.031176] pcmanfm[7486]: segfault at 0 ip b6dad314 sp bfd299ec error 4 in libfm.so.4.0.4[b6d9c000+51000]

pcmanfm ~ crashes
pcmanfm ~/Documents doesn't.
Caja seems to always work.
Memtest OK.

libfm-data:all/xenial-updates 1.2.4-1ubuntu1.1 uptodate
libfm-extra4:i386/xenial-updates 1.2.4-1ubuntu1.1 uptodate
libfm-gtk-data:all/xenial-updates 1.2.4-1ubuntu1.1 uptodate
libfm-gtk4:i386/xenial-updates 1.2.4-1ubuntu1.1 uptodate
libfm-modules:i386/xenial-updates 1.2.4-1ubuntu1.1 uptodate
libfm4:i386/xenial-updates 1.2.4-1ubuntu1.1 uptodate

Status changed to 'Confirmed' because the bug affects multiple users.

I also had this segfault, and deleting the named socket also fixed it.

The only difference I could observe is that the initial connect() call to the socket produced -1 ECONNREFUSED on a failed run (where it already existed), and on a successful run (where it did not already exist) the connect() call produced -1 ENOENT. Everything subsequent looked identical until the crash. Could it just be bogus error handling when a defunct named socket is left around due to a system crash, resume failure, etc?