The issue you are encountering with Milvus likely stems from two potential causes: connection instability and incomplete collection loading. Despite your query operation working correctly, the search operation introduces additional dependencies on the collection being fully loaded into memory and stable connectivity to the Milvus server.

The "connection refused" error suggests that the Milvus server is either not accessible or experiencing downtime at the time of your search request. This could happen if the server address or port configuration in your script does not align with the actual deployment details. Alternatively, there may be intermittent network issues or resource constraints on the Milvus server, particularly if it is running in a containerized or cloud environment. Ensuring that the MILVUS_HOST and MILVUS_PORT variables in your script correctly point to the active Milvus instance is essential. You should also verify that the server is operational and its logs do not indicate any errors related to resource allocation or connectivity.

The "collection not loaded" error indicates that while the collection.load() method was called, the collection might not have been fully loaded into memory before the search was initiated. This could occur due to high memory usage, server resource limitations, or a delay in the loading process. It is critical to ensure that the collection.load() operation completes successfully before proceeding with the search. You can validate this by using utility.has_collection_loaded(collection_name) to confirm the collection's status.

To address these issues, you should verify the stability and accessibility of the Milvus server, ensure that the correct server configuration is in use, and confirm that the collection is fully loaded and ready for search operations. These steps should resolve the errors and enable the search functionality to work as expected.