Guide64.9K views2,708 votes0 replies1,995 following
Diagnosing SQL Developer Connection Failures: A Practical Checklist
When SQL Developer shows a ‘Network Adapter could not establish the connection’ error, the problem is almost always in the network, listener, TNS, or wallet configuration. This guide walks through the most common causes, quick tests, and how to fix each one on Windows, Linux, and macOS.
sqldeveloper