For some time now I have been getting some spurious warning messages at the top of some but not all reports. Can't see a pattern. I get it in Constituent Detail, but not my own report created from in some Mailing reports, but no Membership reports. I hoped an upgrade would sort it and have just upgraded to CiviCRM 5.24.6 and that hasn't made any difference. I don't see it in another CiviCRM site I run which I thought was set up the same. I'm on WordPress 5.4.1. I can live with it but other users will worry.
The warnings are:
Warning: htmlspecialchars() expects parameter 1 to be string, array given in /home/coma6771/public_html/crm/wp-content/plugins/civicrm/civicrm/packages/HTML/Common.php on line 144 Warning: Cannot modify header information - headers already sent by (output started at /home/coma6771/public_html/crm/wp-content/plugins/civicrm/civicrm/packages/HTML/Common.php:144) in /home/coma6771/public_html/crm/wp-admin/admin-header.php on line 9