the metod is deprecated, you have to replace "isSearchBar" with "isLegacySearch" in this files:
#resources/views/vendor/adminlte/partials/navbar/menu-item.blade.php
#resources/views/vendor/adminlte/partials/sidebar/menu-item.blade.php
# Step 1
In this files:
resources/views/vendor/adminlte/partials/navbar/menu-item.blade.php
resources/views/vendor/adminlte/partials/sidebar/menu-item.blade.php
Change
@inject('menuItemHelper', JeroenNotenLaravelAdminLteHelpersMenuItemHelper)
To
@inject('menuItemHelper', 'JeroenNotenLaravelAdminLteHelpersNavbarItemHelper')
# Step 2
Change the method 'isSearchBar' to 'isSearch'