I have installed JMS MultiSites 1.3.16 on a site running Joomla! 3.1.5. When I install the patches, I got the following error message:

installation:

Not OK

Directory found but missing index.php.
The installation directory is required to create fresh slave site. It contains the joomla web installer.

Actions:

Restore the directory

Renamed 'installation' dir:

I am entering the renamed 'installation' dir (which does contain index.php) before clicking Install Patches.

I also noticed that after I click Install Patches, a separate 'installation' directory is created that only contains the folder "application" with the file "defines.php" inside it.

What am I doing wrong?

When you have such kind of message, this mean that the "/installation" with all its content is not restored correctly.

Different solution for that:
1) Restore the /installation directory from you Joomla installation ZIP file.
This solution is recommended when you hare using a Joomla distribution with a specific language (other than the joomla.org).

2) Verify that your server can connect outside to download the "installation" zip file that we have duplicated on our website. We only have the original file with english
Sometime, a firewall forbid such external connection or the "open url" is forbidden.

Try removing (or renaming) the /installation directory to let JMS retry download the "installation.zip" file from our website.

Thanks! I restored /installation from the original unzipped Joomla! installation file and now I get:

“Congratulation, all the patches are successfully installed.”