ImportError: No module named frieght

I had deployed 3 frappe instances in my environment. Initially all were working fine. I tried to install some custom app into it. But was not able to install showing the error

ImportError: No module named freight

my supervisorctl status shows

frappe-demo1-processes:frappe-demo1-frappe-async-worker     FATAL     Exited too quickly (process log may have details)
frappe-demo1-processes:frappe-demo1-frappe-longjob-worker   FATAL     Exited too quickly (process log may have details)
frappe-demo1-processes:frappe-demo1-frappe-web              RUNNING   pid 13136, uptime 0:09:08
frappe-demo1-processes:frappe-demo1-frappe-worker           FATAL     Exited too quickly (process log may have details)
frappe-demo1-processes:frappe-demo1-frappe-workerbeat       FATAL     Exited too quickly (process log may have details)
frappe-demo1-processes:frappe-demo1-node-socketio           RUNNING   pid 13142, uptime 0:09:08
frappe-demo1-redis:frappe-demo1-redis-cache                 RUNNING   pid 13120, uptime 0:09:08
frappe-demo1-redis:frappe-demo1-redis-queue                 RUNNING   pid 13126, uptime 0:09:08
frappe-demo1-redis:frappe-demo1-redis-socketio              RUNNING   pid 13125, uptime 0:09:08
frappe-demo2-processes:frappe-demo2-frappe-async-worker     FATAL     Exited too quickly (process log may have details)
frappe-demo2-processes:frappe-demo2-frappe-longjob-worker   FATAL     Exited too quickly (process log may have details)
frappe-demo2-processes:frappe-demo2-frappe-web              RUNNING   pid 13117, uptime 0:09:08
frappe-demo2-processes:frappe-demo2-frappe-worker           FATAL     Exited too quickly (process log may have details)
frappe-demo2-processes:frappe-demo2-frappe-workerbeat       FATAL     Exited too quickly (process log may have details)
frappe-demo2-processes:frappe-demo2-node-socketio           RUNNING   pid 13116, uptime 0:09:08
frappe-demo2-redis:frappe-demo2-redis-cache                 RUNNING   pid 13109, uptime 0:09:08
frappe-demo2-redis:frappe-demo2-redis-queue                 RUNNING   pid 13112, uptime 0:09:08
frappe-demo2-redis:frappe-demo2-redis-socketio              RUNNING   pid 13113, uptime 0:09:08
frappe-demo3-processes:frappe-demo3-frappe-async-worker     FATAL     Exited too quickly (process log may have details)
frappe-demo3-processes:frappe-demo3-frappe-longjob-worker   FATAL     Exited too quickly (process log may have details)
frappe-demo3-processes:frappe-demo3-frappe-web              RUNNING   pid 13099, uptime 0:09:08
frappe-demo3-processes:frappe-demo3-frappe-worker           FATAL     Exited too quickly (process log may have details)
frappe-demo3-processes:frappe-demo3-frappe-workerbeat       FATAL     Exited too quickly (process log may have details)
frappe-demo3-processes:frappe-demo3-node-socketio           RUNNING   pid 13104, uptime 0:09:08
frappe-demo3-redis:frappe-demo3-redis-cache                 RUNNING   pid 13098, uptime 0:09:08
frappe-demo3-redis:frappe-demo3-redis-queue                 RUNNING   pid 13097, uptime 0:09:08
frappe-demo3-redis:frappe-demo3-redis-socketio              RUNNING   pid 13096, uptime 0:09:08

why is frappe worker showing fatal error

what could be the reason for this error pls help.

regards