The environment variable PATH which is set while invoking the hang analyzer script is invalid, the hang analyzer tries to search for the executable "gdb" in the directories listed in the PATH environment variable since the PATH is set to /opt/mongodbtoolchain/gdb/bin:/usr/bin:xxxxx, the script finds the gdb under /usr/bin and uses it to generate core dump that eventually fails.

PATH="/opt/mongodbtoolchain/v4/bin:$PATH" is the correct way to set the PATH to point to the bin directory.