ESR is to list all the different types of metadata stored in in and quickly explain how that data is used.
The ESR holds descriptions of services that are then implemented in applications that are separate from the repository.
Please refer below step by step guide
ESR Service Modeling - Step-by-Step guide for Outside-In approach
Enterprise Services Repository Troubleshooting Guide
SAP Network Blog: Configuring & Publishing Enterprise Services from SAP Business Suite system into NWCE (Netweaver Composition Environment) Services Registry
SAP NetWeaver Process Integration - Simple Use Cases
Consuming Services with ABAP
How to model and design enterprise services in ESR710
Can u check the following
Go to SPROXY tcode:
Go to-> test connection tab and test all reports.
did u checked all the configuration and tested it properly.
This comes when u do not have connection between R3 and Xi.
make usre that u ahve maintained the RFC connection in SM59 tcode.
also check the INTEGRATION_DIRECTORY_HMI connection.