Oracle SQL Developer新建连接失败求助：Cannot create new connection

Hey there, sorry you're stuck with this connection issue—let's walk through the most common fixes to get you up and running.

1. Double-check your connection details (the #1 culprit!) #

Small typos or mix-ups here are super common. Verify:

• Username/Password: Oracle credentials are case-sensitive if you enabled that during database setup—make sure you’re entering them exactly as configured.
• Hostname: For local databases, try localhost or 127.0.0.1 instead of a network name if you’re having trouble resolving it. For remote servers, confirm the correct IP/hostname with your DBA.
• Port: The default is 1521, but if your database uses a custom port, cross-check with your setup notes.
• SID vs Service Name: Don’t confuse these two! Newer Oracle versions often use pluggable database service names (like ORCLPDB1) instead of the traditional SID (ORCL). Try both if you’re unsure.

2. Confirm the Oracle Database & Listener are running #

If your database isn’t active, you can’t connect at all:

• Windows: Open the Services app (search "Services" in the Start menu), look for OracleService[YourDBName] and OracleOraDB[Version]Home1TNSListener—both should show "Running".
• Linux/macOS: Run these terminal commands to check status:

  # Check if the database is open
  sqlplus / as sysdba
  SQL> select status from v$instance;
  # Should return 'OPEN'
  
  # Check listener status
  lsnrctl status
  # Look for "READY" next to your database service entry
  

3. Ensure JDBC drivers are configured correctly #

SQL Developer usually includes built-in drivers, but they might be missing or outdated for newer database versions:

• Go to Tools > Preferences > Database > Third Party JDBC Drivers in SQL Developer.
• If you don’t see an Oracle driver (named ojdbc*.jar), add it manually. You can find this file in your Oracle database installation folder under ORACLE_HOME/jdbc/lib.

4. Check firewall settings #

If your database is on a remote server, your local firewall might be blocking port 1521. Temporarily disable your firewall (or add an exception for SQL Developer/Oracle’s port) to test if this is the issue.

5. Repair or reinstall SQL Developer #

Corrupted installations can cause weird connection glitches:

• Uninstall SQL Developer completely, delete leftover folders (like C:\Users\<YourName>\AppData\Roaming\SQL Developer on Windows), then download the latest version and reinstall.
• Also, confirm you’re using a compatible Java version: SQL Developer 22+ requires Java 11 or higher. Check your version with java -version in terminal.

6. Test connectivity with TNSPing (Windows) #

Run tnsping <your_service_name> in Command Prompt. If it returns "OK", your network connection to the listener is working. If not, your tnsnames.ora file (found in ORACLE_HOME/network/admin) might be misconfigured. A valid entry should look like this:

ORCL =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = ORCL)
    )
  )

If none of these steps fix the problem, sharing the exact error message you’re seeing would help narrow things down even further!

内容的提问来源于stack exchange，提问作者Doonie Darkoo