Hi there @sfsf123ab,

Yes indeed it could be due to permissions, but what I would suggest is checking your Apache error log so that you could see what the actual problem is rather than the generic 500 error.

You can do that with the following command:

tail -f /var/log/apache2/error.log

With the -f argument, you would see the output of the log in real-time, so you could visit your website via your browser, and you would be able to see the errors populating the log if there are any. To stop that, just press CTRL+C.

You can follow the steps on how to do that here:

https://www.digitalocean.com/community/questions/how-to-troubleshoot-common-apache-issues-on-linux-server

Let me know how it goes!
Regards,
Bobby