Comment # 2 on bug 909661 from Ulrich Deiters

"I guess you have a problem caused by apache 2.2 -> 2.4 transition*)."

Evidently! I do not remember having ever modified httpd.conf, but I cannot
fully exclude it. In order to get rid of all old style directives, I removed
and then re-installed apache2, and the server began to respond.

Then I set "Options Indexes FollowSymLinks" in
/etc/apache2/default-server.conf,
and my website was up and running again.

So the problem is solved. It is a pity that the apache server did not write any
complaints to the log file; it would have saveme some trouble.

Thank you for your help!