Notice Appeared in WP Admin as "Notice: Undefined index: wcp_wpnonce in…"

Hello, I have installed and entered the respective values as required. My pages are so far looking fine, but this notice came up on the top of my WordPress admin page:

“Notice: Undefined index: wcp_wpnonce in….on line 302”

Any way to resolve this?

For the URL to encode, I entered the same URL as that of Remote WHMCS host, is that correct or did this cause that notice to come up?

Please help, thank you.