new error message

Are you using a Controller to render the error page?

In the action method, are you calling:

_pageDataContextInitializer.Initialize(errorPage);

Sounds like you might not be, and the layout/masterpage depends on the page being initialized for some data to be accessed?

would that be a new thing? it has worked all along up until now.

This page data context initializer is new for Kentico Xperience 13, but it kind of replaces Kentico 12's way of initializing the page builder context:

HttpContext.Kentico().PageBuilder().Initialize(page.DocumentID);

If you are using content-tree based routing, page data context initialization is handled for you automatically by the system. But if you're using custom routing (which I guess you might be for your error controller) then you need to initialize the page data content manually.

So it's starting to make sense. I did add a pagebuilder component on my _layout.cshtml. Should I just not have it there? The error page doesn't have any kentico page that corresponds to it.

What do you mean by pagebuilder component?

Have you added a widget inline in your _layout.cshtml? Is it a View Component trying to access the current page by IPageDataContextRetriever? Or something else?

I added this tag to the _layout.cshtml file <editable-area area-identifier="tourcode" />

is there a way to have the error page ignore it?

You should NOT have those in your _layout.cshtml file. Those tags should be in a view or partial view from a controller's action or widget component. Back in PE days, you could add all you wanted to your "master page", but this is a bit different and doesn't work like that.

That's what I suspected and just moved it to a view.

Thanks! someday I'll be a Kentico master. :P