CORS error; mission 'Invoke The API Service Using Generated Client SDK'


I get an error “null has been blocked by CORS policy”. I need more understanding in order to clear this.

I do not wish to restrict access per the stated guidelines in the link above. Why am I getting this error? What is the fix? Does this happen to an end user that may need to use my created application?


Hi Ryan,

Could you please describe how you run the client-side of the “app”?


Thanks, Mark!

I am using the example code in Visual Studio Code, testing on Chrome. Error occurs when selecting ‘Get Instructions’.

I do not have the App_ID or API_KEY set.


I believe it is part of the problem. Please make sure to set APP ID and API Key or use the domain assigned to your app. More details can be found on the following documentation page:

Yes, which is why I mentioned it. I do get errors adding it in also.

Trying to isolate the issue… Thanks!

Is your app in the US or the EU hosting region? The Backendless Console shows it like this:
Data Browser - ConsoleDemo - Backendless 2023-05-30 17-09-50

US Cluster

I am looking into the app identified in the error log you shared and do not see any API services. This is the reason for the error:


That was it! THANK YOU VERY MUCH!!!

(wrong app declared)