It might help you getting responses if you include the exact error message, and other relevant info.

Btw! If you have only one store it's id 0, if you add a second store it gets id 1.

I did. null store id on line 30 in settings. There are no errors in the error log. It was an error shown in the browser, like it does when you have a syntax error in the code, so I wrote the first error thrown.
I went to recreate the error by reinstalling the Amazon Checkout extension (not pay with amazon, but same difference) and this time it installed with no error.

if someone fixed it, thank you. Or it was just a glitch maybe? I installed from my admin - marketplace so maybe it was just a bad install.

Well, it's was really unclear that this had anything with installing to do etc. But I'm glad you got it working anyway.

Next time, be more precise about the issue and where it's coming. And do post the exact and complete error as a quote, then there is no confusion.

I def appreciate you trying to help, thank you. I'll try to be more exact in the future, not used to asking for help as I can usually find the answers online, but Arastta being newish I can't find answers to little things like this.

So after hours wasted on this error the Amazon Checkout extension is only for the UK and Germany marketplace??? That would have been nice to know before installing.
It doesn't even save my info or enable the extension.

I tried Login and Pay with Amazon opencart extension but that didn't seem to work either. Is there a working Amazon checkout extension for Arastta 1.5, preferably with US market? What opencart version is compatible with 1.5?

Pro-tip! Also search for the same errors using OpenCart instead of Arastta, to find more.

The OpenCart compatibility is explained here: https://arastta.org/docs/developers/opencart-compatibility

I know nothing about Amazon Checkout, but the module at the marketplace is most likely from that version of OpenCart (since it's version 1.0.0), and it needs updating to add US support.

I added it to the issues, as a reminder to the core team: https://github.com/arastta/addons/issues/39
- but sure, if someone have the required skills and interest in fixing, they could propose a pull request for it any time.

Ok a few more issues with this extension. I added an Amazon button to the checkout page through the layout manager. I uninstalled the Amazon Checkout extension, but that did not remove the button from the checkout. Reinstalled Amazon Checkout, got the original error I first posted about, refreshed the market page and the error went away. I have no explanation, but I'm assuming theres a bug in the market admin panel, or with this extension. No errors in the error log.

Before reinstalling I cleared all the cache but that did nothing.
Once the extension was reinstalled I was able to remove the button from the checkout page. The button was still saved on my server, but it is only accessible if the checkout extension is installed.

I don't know if this Amazon Checkout extension is going to be updated, or if it was added just for the hell of it, but it's not working properly.

Thanks the tip. I did use the proper the oc version, according to the docs, but the coding format in the extension is different than Arastta. I have noticed this with a couple vqmod/oc mods I've looked at. Some OC 2.2 mods are more compatible than the 2.0.1 so I thought maybe Arastta 1.5 was different than what the doc says.

I didn't even think to check the version of the extension lol. I just assumed it was being worked on by the Arastta team. I'll be sure to look at that for now on.