I was trying web upgrade and ended up in a blank page. The error file shows the following:
text/x-generic error_log ( ASCII text )
[21-May-2020 11:18:27 America/Boise] PHP Warning: Constants may only evaluate to scalar values in …/lib/pkp/classes/db/DBConnection.inc.php on line 17
[21-May-2020 11:18:27 America/Boise] PHP Parse error: syntax error, unexpected ‘?’, expecting variable (T_VARIABLE) in …/lib/pkp/classes/notification/PKPNotificationOperationManager.inc.php on line 374
[21-May-2020 11:19:33 America/Boise] PHP Warning: Constants may only evaluate to scalar values in …/lib/pkp/classes/db/DBConnection.inc.php on line 17
[21-May-2020 11:19:33 America/Boise] PHP Parse error: syntax error, unexpected ‘?’, expecting variable (T_VARIABLE) in …/lib/pkp/classes/notification/PKPNotificationOperationManager.inc.php on line 374