After module installation, updating translations still at 0% I installed Drupal 8.5.6, in French. It seemed to work well, apart from no CSS working, but I corrected by unchecking CSS aggregation in the performance settings.

I decided to install some modules, one by one. Every time I install a module, after I click on the Install button, I get this.


  


After waiting more than 2 minutes (which is abnormal to me), I click on the Extend link to see if the module I am trying to install has been installed. The module seems to be installed, since it is checked, but it is not working. 

So I uninstall that module, and try installing another module, but I get the same result.

Notice that the first modules I tried installing were the Coffee and Admin Toolbar modules. They get installed properly offline.

I have also noticed that using Drupal 8.2.5 everything is fine.

Is there any version problem, or am I doing something wrong?

I changed the PHP version using on the host to PHP 7.1.
After a few time doing something else, I went back to the issue. In fact a lot of JavaScript was not working correctly. 

Then I decided to go back to Configuration -> Performance and unchecked JavaScript aggregator and saved that configuration. See the image below :  



Now everything works fine!!! 

Now I can use admin toolbar's dropdown menu as well as coffee and all the other stuff is working well.

And thank you for reading me.