Internal Server Error show after update from Ver-12 to 13.1.2

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


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 : frappebench13

when we try to open 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


is there is any solution ??

check your logs in /frappe-bench/logs directory

share your web.error.log, frappe.log files log here so we can help you to troubleshoot