Hi @souvikbhaduri,

We appreciate you writing in,

The error might have occurred while adding your GTM code. Could you once check the link below and verify if you have followed the same steps? If not then please add your GTM code as instructed in the link below:

https://www.wpbeginner.com/beginners-guide/how-to-install-and-setup-google-tag-manager-in-wordpress/ . Do write us back if the problem still exists.

Regards,
ThemeGrill Support Team