Seems to be a H2 database bug.
I'll migrate to the latest version of H2 for the next Ubooquity release, that should make this bug disappear.

In the meantime, you can work around this problem by running Ubooquity in any non-root folder (i.e. create a folder on E: and run Ubooquity in it instead of running it directly at the root of your disk).

Took me some time but I added Chnuky Reader as my recommended reader for iPad in the FAQ.

All the files and folders Ubooquity creates (including the cached thumbnails and the database) are located in the "working directory".
The working directory is simply the directory where you are when you launch Ubooquity.
So, for instance, if Ubooquity.jar is in /apps but you want it to create its files in /another/folder/, simply go ("cd" command) in /another/folder/ and run Ubooquity by giving its full path to the java command.
Something like:

java -jar /apps/Ubooquity.jar

If you use a Windows shortcut, the working directory is a field you can define in the properties of your shortcut.

Last way of specifying the working dir: pass the user.dir parameter to java when running Ubooquity.

java -Duser.dir=<your folder> -jar Ubooquity.jar

Replace "<your folder>" by the absolute path of the location where you want Ubooquity files to be written.

Let me know if you have any question.

Couldn't have given a better answer.

The hard (and Seagate specific) part will be to find out if (and how) you can install Java.
Once this is done, Ubooquity will almost certainly be able to run.

Not knowing anything about Seagate NAS, I won't be able to help you more.

It's technically feasible, but why don't you run Ubooquity from the directory where you want it to store the caches and database file ?

Yes, I don't have the problem anymore.
(title edited, by the way)

That's because the regular expression has to match the whole path, not only the folder name (not very intuitive, I agree, but necessary so that you can precisely define which folders you want to exclude in complex cases).

In your case, something like ".*.AppleDouble" (without the quotes) should work.
(there is probably a cleaner regexp for this one, but I'm not a regexp expert)

Let me know if the problem persists.