Error: quartus: xcb_xlib.c:82:xcb_xlib_unlock: Assertion ‘c->xlib.lock’ failed.

Description

If your Linux operating system uses the X protocol C-language Binding (XCB) library (libxcb), the Quartus II software might fail to start with an error similar to the following:

quartus: xcb_xlib.c:82:xcb_xlib_unlock: Assertion "c->xlib.lock" failed.

Resolution

Upgrade you Linux distribution to the latest version or, if your Linux distribution uses libxcb version 1.1, run

export LIBXCB_ALLOW_SLOPPY_LOCK=1

before running the Quartus II software version 11.0.