Fatal error msg when running defender or updating pluggins

This is the msg:
Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 338233 bytes) in /home/content/m/e/i/mein1535/html/wordpress/wp-includes/functions.php on line 354

Is there a size constraint I'm not aware of or need to allocate?
Thanks so much! Randy ;-D