I would like to add some info that may help to narrow the problem.
I have had this crash in PCManFM since i upgraded ubuntu from 16.04 to 18.04 but the same bug manifest in Geany and Chromium as well. The bug could hit PCManFM within a few clicks opening directories and then clicking on a file or can take hours to show up. In the case of Chromium it usually hit at the launch of the browser.
I rebuilt the LibX11 with the supposedly fix mentioned by Tycho Kircher and apparently this has not fixed the problem but the crash is now without the Assertion `!xcb_xlib_threads_sequence_lost' failed.
I would like to add some info that may help to narrow the problem.
I have had this crash in PCManFM since i upgraded ubuntu from 16.04 to 18.04 but the same bug manifest in Geany and Chromium as well. The bug could hit PCManFM within a few clicks opening directories and then clicking on a file or can take hours to show up. In the case of Chromium it usually hit at the launch of the browser.
I rebuilt the LibX11 with the supposedly fix mentioned by Tycho Kircher and apparently this has not fixed the problem but the crash is now without the Assertion `!xcb_xlib_ threads_ sequence_ lost' failed.
I installed only these packages:
* libx11- xcb1_1. 6.4-3ubuntu0. 2_amd64. deb xcb-dev_ 1.6.4-3ubuntu0. 2_amd64. deb
* libx11-
lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.4 LTS
Release: 18.04
Codename: bionic