Looks like one mystery is solved...

.. and it seems like GeekHammer got it right:

Turns out that the line style is called "Ceiling".

Hi @Nospeedy Nos , and welcome!

These maps were made with Profantasy's Campaign Cartographer 3+ (as most maps you'll find in this forum), and using a style called Dungeons of Schley.

Back in late 2017 it was extended with the "Forlorn Cottage" symbols, and from what I can tell Lorelei (OP) was giving it a try.

Oh, wow. Guess we have ourselves a base test? ;)

Anyway, I do have news: after rereading my previous post, I noticed I'm using the metric version of the house settings. So I modified my test case and replaced the house with the one from SS5C Default... and it worked!

So I ended up doing a dozen tests, and while I can't nail the root cause, I ended up recreating a house setting identical to "SS5C m Tiled" (as far as I can tell) and it didn't crash!

I went back to my big map and replaced the offending buildings with ones using my newly-created house setting. And it worked again!

Now I have a way forward. :)

Tech support ticket sent!

Though I do have something else to report. I said in my previous post:

But I did overlook something. My new setting uses a house style "SS5_Tiles" while the original (crashing) uses "SS5m_Shingles". And while I don't fully understand what the option does, I sure can change it. Sure enough, that managed to reproduce the crash.

I tried opening the fcws for house styles, both opened fine. But I don't know enough about house styles to even tell what should I be looking at.

I'm one of the Astral expats. I hadn't paid much attention to VTTs for ages: just relying on printed maps, pencil & paper, or GIMP on the few occasions I had a PC at hand. But then came the pandemic and I started playing with two cousins (we live nearly 1000km from each other)... it simply dawned on us that we might as well take advantage of the acquired familiarity with virtual meetings.

Did my research and landed on Astral (I already had an account, but hadn't really used it). It had a great free tier, but I could still purchase a subscription when I could afford it. I still miss it.

I haven't seen the latest Roll20 interface. I was invited 10 months ago to a private preview for the new-and-upcoming Roll20 interface.. perhaps this is it, but I haven't even logged in lately. Might do that today, seeing as my game was cancelled.

To replace Astral, I landed on Owlbear Rodeo for maps, Discord (+bots) for chat and dice, and cloud-shared fillable PDFs for character sheets (or D&DBeyond for when 5E is the system being played).

On a couple of occasions this year, I've even launched OBS studio to share my CC3+ screen as a camera and just draw live.

Yes. That's the one.

Well, @Steven Nentwig (Steven!) I think the time spent drawing maps is time well spent.

But if you want to get the "best" (or working) versions of each map in the FRIA... this is what this thread has been all about. I haven't updated my personal XLS in a while, but I'll still drop it here in case someone finds it useful:

The 6600 Thri-kreen Village Below Ground.fcw map was introduced in update1, but was then corrupted by update3, so you could grab either it from up1 or up2.

I don't think the maps for Caverns below Haptooth Hill, The Tower of Dracandros, nor Gothyl's Tower were actually drawn for FRIA.

But back to your maps... I like them very much. Thanks for sharing them.

Thanks for the offer @Alberto Giuffrida . It would be nice to have an automated way to do it. :)

Unfortunately, no. There are a few maps that should be fetched from update2. For example, 30005 Aru.FCW was introduced in up2, but was then corrupted in up3 (thought I assume this is more of an exception).

Also, I haven't finished checking them all, I still have 360 maps to check.

Oh, ok.. so it only has to exist in CD+Up3 regardless of status, right?

I haven't tested going directly from CD to Up3... it would be an interesting test.

Come think about it.. I did experience unusual lag (compared to running natively on Windows) while opening a very large map. My best guess would be that wine still has some shortcomings while drawing on screen.

Oh, I'm using Fedora, which has a fame for being bleeding-edge. I don't think it would make much of a difference though. And do note that the results I posted in the link on my previous post is for version 7.12. I wouldn't worry too much about versions tbh.