Dear All Kindly advise us I am trying to update my erpnext from ver 12 to ver 30 as the following step
Step 1:-
cd ~/frappe-bench
bench-update
and checked bench version
Step 2 : bench switch-to-brench version-13 frappe erpnext --upgrade
step-3 bench update --patch
step-4 bench migrate
step-5 bench update --build
and check again version : 
when we try to open 124.0.0.1:8080 following error show
Internal Server Error
Kindly advise us:-
1: how to solve this issue I am stuck at this point for the last week.
2.: how to check the error log in erpnext
Regards.