PHP Notice: Trying to get property 'slug' of non-object

I was hoping someone could shed some light on this. I've tried deactivating ALL of my plugins, but i keep getting pages and pages of the following lines in my debug.log.

any suggestions on how else i might try to repair that error?

[03-Aug-2018 20:11:48 UTC] PHP Notice: Trying to get property 'slug' of non-object in > /public_html/blog/wp-includes/taxonomy.php on line 3994
[03-Aug-2018 20:11:50 UTC] PHP Notice: Trying to get property 'slug' of non-object in > /public_html/blog/wp-includes/taxonomy.php on line 3994
[03-Aug-2018 20:11:50 UTC] PHP Notice: Trying to get property 'slug' of non-object in > /public_html/blog/wp-includes/taxonomy.php on line 3994
[03-Aug-2018 20:11:52 UTC] PHP Notice: Trying to get property 'slug' of non-object in > /public_html/blog/wp-includes/taxonomy.php on line 3994
[03-Aug-2018 20:11:53 UTC] PHP Notice: Trying to get property 'slug' of non-object in > /public_html/blog/wp-includes/taxonomy.php on line 3994
[03-Aug-2018 20:11:54 UTC] PHP Notice: Trying to get property 'slug' of non-object in > /public_html/blog/wp-includes/taxonomy.php on line 3994
[03-Aug-2018 20:11:57 UTC] PHP Notice: Trying to get property 'slug' of non-object in > /public_html/blog/wp-includes/taxonomy.php on line 3994
[03-Aug-2018 20:11:59 UTC] PHP Notice: Trying to get property 'slug' of non-object in > /public_html/blog/wp-includes/taxonomy.php on line 3994
[03-Aug-2018 20:12:00 UTC] PHP Notice: Trying to get property 'slug' of non-object in > /public_html/blog/wp-includes/taxonomy.php on line 3994
[03-Aug-2018 20:12:02 UTC] PHP Notice: Trying to get property 'slug' of non-object in > /public_html/blog/wp-includes/taxonomy.php on line 3994