All of a sudden I'm getting a 500 Internal Server Error on my squarespace buttons through Lead Pages?

Site URL: https://www.purecakeface.com/toss-and-swap

Hey There! I could use some help BIG time! I am using Lead Pages to add Pop-Up boxes where people can opt-in and enter their email address to get onto my email list. I have been using Lead Pages and some coding on my Squarespace site for 2 years now and never had issues. Just recently I created another cover page on Squarespace (opt-in page) and when I viewed it on my computer and clicked on my download button, a "500 Internal Server Error" text popped up on the top of the screen not being able to show the Lead Pages opt-in box. I've attached a screenshot of what the problem looks like. I contacted Squarespace and with their tech support they stated:

"So you will need to review the custom code you added to your site to see what is causing this issue to happen. Custom code can affect areas of your site that you don't think it would and there is no specific reason why it didn't but now it does. Using custom code is an advanced modification of our platform and outside our scope of support.  You can see the button working by place your site in safe mode you do this by using your url https://mara-lerner.squarespace.com/config and placing the work safe at the end like this https://mara-lerner.squarespace.com/config/safe. This disabled all scripting you added to the site. I am sorry there isn't more I can do to assist I can only confirm that custom code is the cause of the issue since Squarespace doesn't offer any custom code support. But you can try hiring someone through the Squarespace marketplace to assist you."

The custom coding that I have on my site is required as far as design aesthetics and requirements such as removing the cookie box on my opt-in pages, etc. So this can't be all the other coding on my website for design purposes when this has no relationship to my opt-in buttons with integrating Lead Pages URl links and coding. I've contacted Lead Pages via email to explain this situation as well, and waiting for a response, because I'm not sure if this is a Lead Pages or Squarespace issue. 

If someone can help me on this, that would be greatly appreciated.

Hey there!

Have you tested your other pages that use Lead Pages? Do they work correctly? The first steps with custom codes/scripts is isolating the problem. If the other pages that use the Lead Pages plugin work correctly, I wouldn't think that it's a plugin or script error but something to do with Squarespace or the "toss-and-swap" page itself.

However, if you have other pages that do not work, it's possible that the Lead Pages codes are no longer compatible on Squarespace or may need to be updated.