I migrated my OJS 3.1.2-1 journal to another server with same domain. After migration I got below error PHP Parse error: syntax error, unexpected ‘?’ in /lib/pkp/lib/vendor/illuminate/support/Str.php on line 681
in Archives Page and Submission Page after Login
I tried every possible solution including PHP version 5.6 7 7.1 and 7.2.
I also clear cache after every php version change but not solved.