[quote=Scippy;1583]I have to correct myself, the problem appears only if I open the checkout page with the admin user, i.e. without a checkout process in progress. Maybe that's right?[/quote]

This sounds like it maybe should be in a new forum thread, but...

The error message in this case appears to maybe be missing updates from merging your viewset.

https://hotcakescommerce....doesn-t-work-anymore

[quote]This sounds like it maybe should be in a new forum thread, but...[/quote]
...it could be, but the search in this forum doesn't work and the questions inevitably are duplicate ...

[quote]The error message in this case appears to maybe be missing updates from merging your viewset. [/quote]
how can it be an error in the viewset if the error persists even if I try to delete all the contents of the \ Views \ Checkout \ Index.cshtml ??

Deleting the contents is not a true test because it will result in a different result and error altogether. One thing that's important to remember is that Razor view cache can be pretty resiliant. This is why the PDBs are an important troubleshooting step, because that's one of the few ways I see that consistently clears the Razor cache.

Hi Will, I have identified how to reproduce the error. it is sufficient that once you arrive on the checkout page during a normal sales process, you clean the browser cookies and reload the checkout page, the error will appear.
It therefore seems that the exception is related to the lack of some cookie that is created during the purchase process.
so if you reach the checkout page directly without first adding a product to the cart, the exception is thrown, after adding a product to the cart, even if the cart is emptied, the exception disappears but clearing the browser cookies the exception returns.
Let me know if it needs to open an issue on Github.
Regards.

@skippy Did you ever find a fix for this?
THANKS!