Recently, I posted about how to create RESTful services using ORDS right from SQL Developer. Most of the users have reported me that they are facing 502 Host not resolved problem while connecting to the server on SQL Developer. The SQL Developer 502 host not resolvable error occurs when you do not get the correct response from the server or headers sent by the client is incomplete. This is usually caused by temporary files and caches stored in the browser or the operating system. As many users were reporting the issue, I was not in an idea of having it resolved as I could not reproduce the same issue. But luckily, I was not able to close SQL Developer properly and next time when I opened SQL Developer to connect to RESTful Development Services, it showed me a popup, "Cannot connect to Connection. HTTP/1.1 502 notresolvable". I did not make any changes to the server and also when I checked the status of ORDS services on my virtual machine, it was running perfectly. I tried to reset settings of SQL Developer. It did not help, however, for some users have reportedly told that resetting SQL Developer has helped resolving the issue. Here is how to reset SQL Developer settings.

  1. Export all your connections to an XML file.
  2. Close all SQL Developer window.
  3. Go to Run (or press Win Key + R) and type %appdata%
  4. Go to SQL Developer folder
  5. You can see a folder named, in a similar format: "systemXX..."
  6. Rename the folder.
  7. Now open SQL Developer and it will ask you like it is starting for the first time.

If your problem was still not resolved. Here is another solution that worked for me.

  1. Close all SQL Developer window.
  2. Go to Run (or press Win Key + R) and type %temp%
  3. Delete all the files in the folder.
  4. Open SQL Developer.

This method will not reset any settings but just delete all the temporary files. Note that deleting temporary files from the %temp% folder will also affect any open programs. After trying out a working method from either of the above, try connecting to REST Data Services again by providing the credentials. It should work. Please let me know in comments if you have any other queries.