Solution suggested is enrolling back to dev preview and updating to latest OS version available, after which you should be able to update to Lumia Denim, if it is available for your device. This sort of confirms that if you are on developers preview already and updated to latest version, you will get Lumia Denim automatically.
If your phone was enrolled in the Windows Phone Developer Preview Program but was reset or otherwise removed from the program, the Lumia Denim update will not be available, or reports an error 8018830f. To recover this, first check your phone for any of the updates for the Developer Preview and then install the Lumia Denim update.
You may also use the Lumia Software Recovery Tool to remove the Developer Preview Program and return your phone to the official Lumia update. You can download the tool at www.microsoft.com/mobile/support/recovery-tool.
The second option in such cases is obviously using “Lumia Software recovery tool“.
Thanks Monti for the tip. Cheers!!