I use a main domain with the application that calls the route through the client's Domain Alias, but when placing 20 clients the server causes error 500, and can only resolve with snapshot. If dear colleagues can collaborate by sharing knowledge, I would like to thank you in advance.
The number of clients and the 500 error are not directly related; maybe you uploaded too much data and your system ran out of disk space. Look into the error.log of the website to find out why this happens. Also, restoring a system to a previous snapshot just because of a 500 web server error is normally not nescessary.
Yes, I solved the 500 error, it was a syntax error in my code, but now Apache does not start and does not generate the Lets Encrypt certificate.
Then you likely changed something manually in Apache config, as ISPConfig has automatic config rollback for its own changes in case something fails. or you manually used e.g. certbot and did not use ISPConfig SL option. manually using certbot also damages the config and Apache will fail to start afterwards. Check the web server error.log to find out why Apache fails now.
Wow, with so many attempts to start Apache, it may have changed something, but I didn't create the lets encript manually. Now I did the snapshot, it went back to 15 Aliás. I'll look at the logs and try again to add more Aliás. If there are other failures in this sense, I'll come back with another request for help. Thank you very much for the great help.
