In this document we will referred to the Browser, Gateway and Backend system. If you have an embedded installation both systems are the same. If you have a cloud gateway environment you should take into account that some things mentioned related to the gateway have to be checked in a different way.
User Interface issue
Check if there's any error in the browser console (F12).
Please check if the following KBA is relevant for you: 2743849 Resource not found for the segment 'XXXXXXXX'
Errors mentioning ERROR_LOG on SAP Gateway you should use transaction /n/iwfnd/error_log in the Gateway system. You can find further information in note 1797736 - Troubleshooting Guide for SAP NetWeaver Gateway For SAP Cloud Patform, OData provisioning please check note 1964574 - Troubleshooting Guide: SAP Cloud Patform, OData provisioning
You can either get to this point if an error has been found in the Gateway system identified as Backend error or in case you want to analyze the data shown in the application.
Backend errors can be found in transaction /n/iwbep/error_log . You can find the affected objects in the call stack of the errors.
In order to technically analyze the behavior of the backend system you can set external breakpoints for the affected user. If no error appears you can start with the odata provider class, or use traces or the ANST tool to determine the object where you want to set the external breakpoints.
For Authorization issues