This morning one of my Apple Software Servers (ASUS) was not supplying updates. When checking the swupd_err.log in Server Admin I saw the following repeated hundreds of times:

Syntax error on line 241 of /etc/swupd/swupd.conf: Port must be specified

Below can be found more details and the solution.

Discovery

In the Server Admin GUI I checked the value of the “Provide updates using Port:” & sure enough, it was empty.

I tried entering a port & clicking save, to no avail. I also tried stopping the service, entering a port & restarting the service. Again no luck.

So i removed onto the server, made a copy of /etc/swupd/swupd.conf. I opened the file & had a nose @ line 241.. sure enough it was incorrect:

Listen *:portToUse

I tried stopping the Software Update Service & then edited line 241 so it read:

Listen *:8088

However, on restarting the service the file changed the value back to:

Listen *:portToUse

Solution

So with the Apple Software Update Service running, I edited line 241 so it read;

Listen *:8088

The error log started to fill with the normal gumpf:

[Wed Apr 11 09:04:05 2012] [notice] mod_bw : Memory Allocated 32 bytes (each conf takes 32 bytes)
[Wed Apr 11 09:04:05 2012] [notice] mod_bw : Version 0.8 - Initialized [1 Confs]
[Wed Apr 11 09:04:05 2012] [notice] Apache/2.2.21 (Unix) configured -- resuming normal operations

I then tested clients updating against the server & voila!