I've been trying to fix this for a while. I downloaded the Ultima Patcher, which worked for updating the signs (Thank god!), but music will not play. I can get music to play when the Ultima Patcher runs it's test, but the music does not work in game. I think it may have something to do with the music enable key 'CTRL + V' which the manual states will toggle music on/off, but whenever I hit it all I get is text saying "1.16" which I'm assuming is a version number. So disappointing! The music is a bit part of the experience!

I would love it if someone could help me out. Thanks!

I know this topic is almost a year old, but since I recently did install the game and found out how to add the music back to it, it might be useful to somebody else.

Go here to dowload the "U5 Upgrade Release 1.0" package: http://exodus.voyd.net/downloads/
Go here to download the "cwsdpmi.zip" file (which is missing from the above package): https://teadrinker.net/tdold/mr/download.htm

Unpack all that in the Ultima V installation folder, overwriting the original files.
Follow the instructions in the readme.txt. This will require you to mount the installation folder in DosBox, which you can do easily by dragging-and-dropping the folder onto the DOSBox executable.

Create a shortcut of the DOSBox executable (from the DOSBOX folder) on you desktop, then right-click it to go to Properties. You'll see the "target" field. Add the path to the .com file (NOT the .exe file) at the end, so it would look like this (do use quotation marks):
"C:\GOG Games\Ultima 5\DOSBOX\DOSBox.exe" "C:\GOG Games\Ultima 5\ULTIMA5.com" -conf "C:\GOG Games\Ultima 5\dosboxULTIMA5.conf"

The -conf argument loads GOG's configuration so you get full-screen and other niceties.
Adapt the paths according to your own installation, of course.

Or just use the Ultima Patcher, that's much easier...
http://www.pixsoriginadventures.co.uk/category/ultima-patcher/

He said he did, and he was asking because he still didn't have music.

Then Maybe I didn't type all that for nothing. Good.

I had this exact issue! I'm posting what I did here for posterity.

I was running Ultima 5 using GOG Galaxy. I like how it saves how many hours I've spent on the game, and it's little user interface.

However, the dosboxULTIMA5_single.conf file it creates, by default, uses ULTIMA.EXE to execute the game. This does not play all of the nice MIDI music that is installed using the Ultima Patcher.

So, what I needed to do, was edit the dosboxULTIMA5_single.conf file, and change "ULTIMA.EXE" to "ULTIMA5.COM" and, viola, I have music!!!

But is there a way to turn the music off in game once you have upgraded it?

Run the original shortcut that was installed by the GOG installer. The one that has a Target value WITHOUT "ultima5.com" in it. It will be similar to this:

"C:\GOG Games\Ultima 5\DOSBOX\DOSBox.exe" -conf "..\dosboxULTIMA5.conf" -conf "..\dosboxULTIMA5_single.conf" -noconsole -c "exit"

This will let you run the game without music. Unfortunately, I don't think there's a way to toggle the music on and off while in the game.

Another way is to run u5cfg.exe and disable the MIDI music that way.