Bonjour Edwin,
I try to create a new slave site (in an environment, where there are already a number of existing slave sites). The configuration in JMS works well and everything looks as ususal...
the "Deploy directory" points to the "Master site directory" and the DNS seems to work as expected.

However, when I browse to the actual slave site and expect the INSTALLATION to start, all I get is a "white page" and an "/index.php" HTTP 500 error in the server's error log.

How can i get more information about what is going wrong?
Best regards
Ruediger

An error 500 is an "Internal Server Error".
You have to try access your server error log to try get more info on the reason.

A possible place is a problem in the htaccess that may cause an internal server error when there is a syntax error. (I don't think this is the reason here but who knows)

If you are redirected on the "/installation/index.php" that means that the "configuration.php" does not exists in the slave site directory.
If you have created a "fresh slave" site, this is normal that you are redirected to the Joomla web installer.

You may perhaps also have to verify the permission of the directory.
Some server configuration may return a 500 error when you have a directory with a permission 777


Can you precise your Joomla version.

Remark:
Deploy directory and DNS are 2 differents thinks.
The DNS create the relationship between a domain name and its IP address.
The IP address identify the server.

Once you are on the server, this is apache that make the relationship between the domain present in the URL and the "Document root". Its location on the disk.
You have to verify that the "document root" and the JMS deploy directory have the same value.

If you are using cPanel, check you "Addon Domain" or "Subdomain" to retrieve the "document root" value.

Hello Edwin,
i am still fighting this issue (was busy with other things though)...

"Permissions" should not be an issue, the whole implementation is running on a APACHE webserver within a WINDOWS Server 2012 environment (so permissions are not an issue).

Versions: Joomla 3.4.3, JMS 1.3.50basic, Patches 1.3.46

I can confirm that the DNS and APACHE are actually working as expected:
when I upload a simple php-script to the root directory of the JMS installation, I can successfully access this script with the URL of the new slave site.
example: www3.astronomicalheritage.org/undex.php

when I address the index.php (with the URL of the new slave site) of the same directory (which is defenitly existing), I get the SERVER 500 error in the webserver-access-logfile, but no "error message" in the error-logfile at all!
example: www3.astronomicalheritage.org/index.php

Other slave sites in this JMS installation are working properly!

I am a little bit "out of ideas" and would appreciate any guidance!
Best regards
Ruediger

First comment, I see that you are using Joomla 3.4.3 and therefore I suggest to use the JMS 1.3.53 that fix some J3.4 comptabiity.
I don't think this is the reason of the HTTP 500 but the update may help.

I am wondering if the /installation directory is present and if you had a previous joomla version installed with JMS before (ie. J3.3).
If this is the case, I suggest that you remove the /installation directory and that you perform a JMS check patches to re-install it. This is just to be sure that the /installation match your J3.4 version.

Verify that in the slave site, you have under the /installation directory a set of short cut that point to the master /installation directory.

hello edwin,
thanks for your reply.

As suggested, I updated to JMS 1.3.53

the installation directory indeed was present, but as you suspected, it was most probably from an older version (directory and file dates were 2014-07-11 !). I removed the whole /installation directory and "applied the JMS patches".
Now the installation directory is back there with current date (so this should be OK)

My slave sites (all of them for this master site) are deployed into the same directory as the master site, so I only have the "master" installation directory. There is no "in the slave site /installation directory" (or am I misunderstanding something here?)

But I am still getting the SERVER 500 errors when accessing the ROOT/index.php (but no errors, when accessing the ROOT/undex.php, which is just a test to verify the correct server directory is addressed by the URL).

Other slave sites, as mentioned before, are working correctly

Any other ideas?

hang on a moment, am checking something...