topic Re: Still having issues with extended layer support in Fusion Electronics Forum

Still having issues with extended layer support

Joseph_RB — Tue, 27 Jan 2026 16:50:29 GMT

Hi,

I'm still having some issues with libraries and extended layer support. I thought this was the same as a previous problem as my design includes a part with a polygon on the bottom layer and I was seeing three copper layers: ct, c16 and cb. I believe my library doesn't have extended layer support (is there a way to upgrade libraries?), so assumed that was the problem again.

After experimenting, I've realised that if I make a simple schematic, e.g. with a couple of caps, then click 2D PCB, the new PCB has two layers: ct and c16 (no cb). If you flip an SMD part to the bottom layer, the pads disappear. If you then issue the command layer cb, the bottom layer appears, but trying to route anything causes Fusion to crash:

If I then go to the Layer stack and change to 4 Layers and back to 2 Layers, everything seems to behave, so I can continue working for now, but it doesn't feel quite right! I think this is a new problem as I would have quickly come across this on recent designs. I'm not sure if something is misconfigured with my Fusion install or it is a problem with a recent update?

Very best wishes,

Joseph

Re: Still having issues with extended layer support

Joseph_RB — Tue, 27 Jan 2026 19:52:08 GMT

After further investigation, the problem seems to stem from the default DRU from Library.io which appears to be set up for the bottom layer being c16. Once I'd switched to a local DRU (e.g. the default from the examples directory), things work as expected.

I usually switch to a custom DRU when designing a new board, but I hadn't considered the default settings would be causing a problem.

This still seems like a bug to me, as the program should work with the default settings and as far as I can tell, Fusion uses the DRU from Library.io by default (unless the option is changed in preferences).

I hope this info is helpful.

Best wishes,

Joseph

Re: Still having issues with extended layer support

jorge_garcia — Tue, 27 Jan 2026 22:10:48 GMT

Hi @Joseph_RB ,

So this is something we have seen with a couple of users. We are still investigating but for a few users the DRU that gets loaded in new designs is not the correct one. The solution to avoid all of that is what you did, which is to adjust the layer stack and go back to whatever layer stack you want.

Let me know if there's anything else I can do for you.

Best Regards,

Re: Still having issues with extended layer support

Joseph_RB — Wed, 28 Jan 2026 22:19:47 GMT

Hi Jorge,

Thanks for the reply. Good to know this is being looked into. Since my last post, the bottom layer polygon in the library has spontaneously moved to layer c16 again. I've haven't changed the design rules, but I did update the library. I'm not 100% sure if this caused the bug to reappear.

If I could upgrade the library to be 64 layer, maybe it would help. Is this possible?

It is a little unnerving to have a features on a design suddenly disappear!

Joseph

Re: Still having issues with extended layer support

jorge_garcia — Wed, 28 Jan 2026 23:16:19 GMT

Hi @Joseph_RB ,

I hope you're well. The libraries can not be updated they are converted when inserted into a design. Now one thing that is important to understand, when working with your design files both(sch and pcb) have to be legacy files or both have to be extended layer support. You can't have a mix, so if for example you uploaded and old EAGLE schematic and then tried to make a board from it in Fusion you would get this mix. The way to avoid this, is to create a new schematic and insert the legacy design into it.

See if this solves it for you.

Best Regards,

Re: Still having issues with extended layer support

Joseph_RB — Thu, 29 Jan 2026 07:53:04 GMT

Hi Jorge,

It is a new electronics project (created this week), using a library created last year. So, both PCB and schematic are new.

I'll see if I can find steps to recreate the problem.

Joseph