SyntaxError: Unexpected end of input OK

[mnowee]

When updating the orderstatus, I get a popup saying: "SyntaxError: Unexpected end of input OK "
I cannot update the status.
Also the same message is given when manually adding an order, so not via the shop/frontend, but via the admin/backend.

I use Opencart v 2.0

You can see it yourself; I found out the same issue exists in the demo shop at demo.opencart.com/admin. Please try to update the orderstatus of an existing order, you'll get the same error.

[danielkerr]

because no api has been setup on the demo

make sure there is nothing blocking the request from the admin to frontend.

[mnowee]

how can I check that?

[onlinephilately]

I have the same issue. Have an API set but still get this Error.

[mnowee]

forgot to mention. My problem is solved. I had the website protected because it's still under construction. setting the API and removing this protection fixed my problem.
So as indicated by danielkerr, you have to make sure there is nothing blocking the request from admin to frontend

[onlinephilately]

Thx for your comment. What can block the request from admin to frontend?

The site is not in maintenance mode and the API is there. Can it be that the site is in a subfolder (to root where an older OC is live)?

Any ideas are welcome!