I checked with all versions of PHP it has nothing to do with this.
I also checked error_log, no error was recorded.
Of course I get this error in the browser console :
jquery.colorbox-min.js?ver=1.3.20:4 Uncaught TypeError: e(...).live is not a function
at at (jquery.colorbox-min.js?ver=1.3.20:4)
at s.fn.init.e.fn.<computed>.e.<computed> [as colorbox] (jquery.colorbox-min.js?ver=1.3.20:4)
at HTMLInputElement.<anonymous> (urvanov_syntax_highlighter.te.min.js?ver=2.8.20:1796)
at Function.each (load-scripts.php?c=1&load[chunk_0]=jquery-core,jquery-migrate,utils&ver=5.6:2)
at s.fn.init.each (load-scripts.php?c=1&load[chunk_0]=jquery-core,jquery-migrate,utils&ver=5.6:2)
at Object.base.bind (urvanov_syntax_highlighter.te.min.js?ver=2.8.20:1791)
at urvanov_syntax_highlighter.te.min.js?ver=2.8.20:1557
