I run Civi on Drupal. After upgrading from 5.4.0 to 5.10.0, any report I open shows 4 warnings at the top:
Warning: Illegal string offset 'attr' in HTML_QuickForm_advmultiselect->toHtml() (line 807 of /home/tamera/www/dev/sites/all/modules/civicrm/packages/HTML/QuickForm/advmultiselect.php).
Warning: Illegal string offset 'text' in HTML_QuickForm_advmultiselect->toHtml() (line 808 of /home/tamera/www/dev/sites/all/modules/civicrm/packages/HTML/QuickForm/advmultiselect.php).
Warning: Illegal string offset 'attr' in HTML_QuickForm_advmultiselect->toHtml() (line 821 of /home/tamera/www/dev/sites/all/modules/civicrm/packages/HTML/QuickForm/advmultiselect.php).
Warning: Illegal string offset 'text' in HTML_QuickForm_advmultiselect->toHtml() (line 822 of /home/tamera/www/dev/sites/all/modules/civicrm/packages/HTML/QuickForm/advmultiselect.php).
Any ideas?