Hi,
I have the same problem in my website. After version 2.6.0 the site crashes.
Did installing “mbstring” fix the situation?
This is the DEBUG_LOG:
[05-Jul-2023 07:33:38 UTC] PHP Fatal error: Uncaught Error: Call to undefined function mb_convert_encoding() in /home/pes60259/public_html/wp-content/plugins/ultimate-member/includes/core/um-filters-profile.php:69
Stack trace:
#0 /home/pes60259/public_html/wp-includes/class-wp-hook.php(308): um_dynamic_user_profile_title('<img src="data:...', 5917)
#1 /home/pes60259/public_html/wp-includes/plugin.php(205): WP_Hook->apply_filters('<img src="data:...', Array)
#2 /home/pes60259/public_html/wp-includes/class-walker-nav-menu.php(228): apply_filters('the_title', '<img src="data:...', 5917)
#3 /home/pes60259/public_html/wp-includes/class-wp-walker.php(147): Walker_Nav_Menu->start_el('<li id="menu-it...', Object(WP_Post), 0, Object(stdClass))
#4 /home/pes60259/public_html/wp-includes/class-wp-walker.php(247): Walker->display_element(Object(WP_Post), Array, 0, 0, Array, '<li id="menu-it...')
#5 /home/pes60259/public_html/wp-includes/nav-menu-template.php(616): Walker->walk(Array, 0, Object(stdClass))
#6 /home/pes60259/public_html/wp-includes/nav-menu-template.p in /home/pes60259/public_html/wp-content/plugins/ultimate-member/includes/core/um-filters-profile.php on line 69
Best regards