Prestashop 1.7.x installation & Error 500

[bearly]

Hello,

 

I installed 4 times of 4 different domains on the same server Prestashop 1.7.1.1.

 

 

Everytime when I want to start the installation, my domain doen't resolve and I get an error 500.

 

My solution was:

chmod 644 on these files: install/index.php, admin/index.php, admin/ajax.php, admin/ajax-tab.php, index.php.

 

 

I just wanted to install another shop on the same server but this time my solution won't work.

Neither with ftp uload nor zip upload on the server and extraction.

 

Exact the same procedure, the same server, same ftp app or extraction on the server, same solution with chmod.
The only difference is that I had to download again the installation files because I did not had them anymore. 

Download them 3 times and tried it 3 times. Stil getting error 500.

 

Any ideas why my solution worked 4 times and now not?

Edited May 11, 2017 by bearly (see edit history)

[tuk66]

What is in the server log?