Hi Humayon. Yes, I did that. It fixed the issue. Thank you.
Hi Tanvir. Seems like the culprit is the WPDM – Page Template plugin. I disabled it and fixed the issue. Thanks for your responsiveness.
Thank you for your response. I tried deleting the plugin and reinstalling it to the latest version (3.2.12). However, the issue still persists. The same error occured.