Hi @lavgee

When the website was updated, it probably removed some files - including index.php or index.html of the directory you're trying to view, which is why you get that error, since directory listing is not something that is enabled by default.

Which website system do you use?

You can see more detailed errors in the error log, which is located in:
If using Apache, it's default location is /var/log/apache/error.log
If using Nginx, it's default location is /var/log/nginx/error.log

There is a possibility of mis-configuration after the website update -- that is, wrong file permissions are restricting the server to access the files. You should check the File permission of your web root directory which contained the index.html or index.php files.

For diagnostic correction, allow permission for all by typing:

sudo chmod -R 777 /path/to/index.html file/
and then;
sudo chown -R [username]:[group] /path/to/index.html file/

where username is the 'username' you use to login to the Droplet, and group will be www-data if your web server is Apache.

Please let us know if this tip solves your problem. If not. then we will have to correct the 'ErrorDocument' attribute in apache configration file or the attribute 'AllowOverride' in .htaccess file.