Did the transfer involve a change to the fully qualified domain name of your site? If so, one needs to do a change to config.php and a search and replace in DB tables for old site -> new site. The config.php file needs to be globally readable by all.
Is the DB user set up correctly in new site? Is DB server localhost or a remote DB server? Check config.php
Check ownerships/permissions of code directory, subdirectories, and files.
Does new hosting have a WAF (web application firewall) that's blocking?
Can you take a screen shot of the files in moodle code directory?
What do you see in your web server error logs?