Thank you for the post.
“on a plain vanilla 10.10.3 Mac mini”
To confirm this is regular Mac OS X and the Server.app is NOT included?
FileMaker Server 13 is tested to be compatible with Mac OS X 10.10.3 as long as the Server.app is not present.
“So how do I fix this problem?”
1. If the Server.app is installed, then uninstall or move the Server.app to another computer.
2. Restart and uninstall FileMaker Server 13 using the current full v5/v9 installer.
3. Backup the databases first, then remove or rename the FileMaker Server folder (Macintosh HD/Library/FileMaker Server/).
4. Reinstall FileMaker Server 13.0v5/9 using the full installer.
“And do I really have to start the web server in Yosemite manually using terminal?”
From the "Before you begin" section of the FileMaker Server 13 Getting Started Guide:
"OS X: The web server included in OS X does not need to be enabled; if it is enabled, ensure that no existing website uses port 80 or 443. The installer creates a separate web server instance and enables it for FileMaker Server to use on these ports."
Additionally, from Chapter 7, "Setting up the web server" from the same guide:
"Using the Apache web server in OS X
You do not need to enable the Apache web server that is installed with OS X, nor do you need to have the OS X Server application installed. In fact, the FileMaker Server installer creates its own instance of the Apache web server on both the master and worker machines and configures this web server to use port 80 for HTTP and port 443 for HTTPS; on the master machine, the installer also configures its Apache web server to use port 16000 for Admin Console via HTTPS. If you have enabled the Apache web server that is already installed with OS X, the FileMaker Server installer prompts you to let it disable any existing website using port 80 or 443 before it can continue.
If you have the OS X Server application installed and use it to enable any HTTP services (for example, websites or the wiki), the existing Apache instance may be re-enabled after FileMaker Server is installed. Therefore to ensure the Apache instance used by FileMaker Server works normally, you may need to configure any other HTTP services to use different ports from the ports that FileMaker Server uses, disable other HTTP services, or uninstall the OS X Server application."
Thank you for your reply...
Yes, plain vanilla as in no OS X server management software installed. :-)
As you correctly point out the solution was to use the FM 13 server 13.0.5 full installer.
Doing so sets things up automatically.
I somehow managed to miss the fact that there was a FM 13.0.5 full installer available and tried to install the original version before upgrading to FM 13.0.9, which of course caused my problems. :-(
The idea of needing to activate the OS web server instance came from reading posts that were probably from before the release of the FM 13.0.5 software suite.