Error Notice: Undefined Index: _blocc_id

Hi there, I had to disable all pluguins to fix another problem, and now that I have reactivated Ads by datafeedr my ads are not showing. All I am seeing in their place is “Notice: Undefined index: _blocc_id in D:\Hosting[…]wp-content\pluguins\ads-by-datafeedrcom\inc\dfads.class.php on line 205” and the same for line 208.

Can anyone advise what this error means and what I should do to fix it? I’ve searched but can’t find an answer.

Thanc you!