Purchased Avernum Complete Saga before.
Installed Avernum4 on my Macbook Pro, OS is latest update, 10.11.2 EI Capitan. Launched the game, found it was unregistered copy, registration code is 9497. I bought it long time before, it should have been registered.

Please help to fix it.

Appreciations.

PS, Avernum 5 & 6 is registered copy in the very same package.

Back up your saves and try reinstalling.

This just happened to me with Avernum 4 as well, even though I just downloaded the game today (I bought the entire series from GOG two or three years ago). Stupidly, I didn't check to see whether it said "registered" or not; I just assumed. I'm not sure what good reinstalling would do, since I installed it just now. I'm fairly sure this is the first time I've ever installed this particular game.

I'm not sure how to back up my save before reinstalling: making a duplicate of the files doesn't work (it just says "Estimating time…" and never starts the process), and trying to move them creates an alias rather than actually moving the files.

Sounds like it might be time to drop a line by both GOG support and Spiderweb software.

Wow, I am having the same issue as well, but with Avernum 5. 4 was "registered" and I beat it. 5 is supposedly "unregistered" even though I bought all these games as part of the complete Avernum collection a long time ago.

I emailed GoG support, but haven't heard back from them yet. Hopefully it's just a matter of it being the holiday season as well as a weekend.

One thing I thought might be the culprit is GoG Galaxy, as I recently told Galaxy to update all my games, but I notice Avernum 5 is listed as incompatible. However, I have tried deleting the game and downloading it again from GoG's website, and the problem remains.

Another peculiar thing is that these posts only started appearing in Dec 2015. Could it be a problem introduced in the latest OS X, or perhaps in the latest Avernum 5 update? I am running OS X El Capitan 10.11.2 on my MacBook Pro, same as the OP.

On a Mac, holding down the Option key while you drag-and-drop the selected file(s) or folder(s) will copy them to the new location and keep the originals. To select multiple files in the first place, click the first, hold down Shift, and click the last one. Alternately, Command-click a file to individually select or deselect it when dealing with multiple files.

For Avernum 4, the save files are hidden in the application itself. You have to right-click to "Show Package Contents." They are in Contents>Resources>game>Avernum 4 Files.

Update: I heard back from tech support and they solved a separate issue. I'll keep you all updated about the "unregistered" issue.

I had the same problem with Avernum 4 and Avernum 5, Macbook Pro 10.8.5, and also have a support ticket in with GOG. Also Avernum 3 crashes at the Wineskin stage and never launches. I haven't tried the others yet because I have the remakes of 1 and 2 and the iPad version of 6.

exactly the same set of problems I am having (but on a 10.9.5)
I could not contact GOG following the "technical issue" link for some reason, but I contacted them using the general enquiry form, waiting for a reply.

Support has solved the unregistered copy, by updating the installers

Also Avernum 3 now works as well thanks to support: the trick here was to update the version of Wine from the Wineskin app that can be found inside the game folder.

I uninstalled and reinstalled mine; it turns out that the game is "unregistered" if I open it from the Finder, but it's fine if I open it via Galaxy. Problem solved, I guess. And I did manage to make a copy of my old save file first.

Thanks for the heads up. I skipped to Avernum 6, which I've almost beat on Torment (a true challenge!). I just downloaded the new version of Avernum 5 and the issue has been solved. Liches may extend their lives, but I can now extend my lack of life further!

Thanks!

Received reply from the support staff, uninstalled and install Avernum4 once more, it showed registered copy!