Dear Adam,
thank you for your immediate reply. I have to admit that I am not a very skilled web developer nor system administrator and was not sure what you meant by "catch the request"... So, I just turned on error logging and I have tried to change the global signature again. The only error I get in the log file is: "[Mon Oct 14 11:08:50 2013] [error] [client 160.85.104.70] File does not exist: /path-to-my-html-root/epesi/favicon.ico", which I guess is unrelated.
In the meantime, I also set up a local web server (Apache/2.4.3 (Unix), PHP/5.4.7, 5.5.27 MySQL Community Server) and turned on php error logging in php.ini. I checked that PEAR is in php's include path and set up a mysql database and user:
CREATE DATABASE epesi;
GRANT ALL PRIVILEGES ON epesi.* TO 'epesi'@'localhost' IDENTIFIED BY '.........';
Thereafter, I installed epesi-1.5.3 as well as epesi-1.5.4 on my own using the zip file and once using the easyinstall.php script. Both methods installed without any difficulties, i.e. the "system requirements check" results where all green and everything went smooth including initial system setup. However, when I try to change the global signature, I still receive "alert('Invalid request');", but no error was logged in the error_log file. Any suggestions are greatly appreciated.
Best regards,
Flavio
