Import / export and installing problems

Hi friends,
I have installed ojs 3.0.1 on ubuntu 16.10 localhost with LAMP. It works right, but I can’t import nor issues neither users from ojs 2.4.x. I’ve read the post from forum about that, but when I am installing ojs 2.4.8 locally, I get blank installation page. Looking in error-log I see that:

[Thu Jan 05 13:25:32.681006 2017] [:error] [pid 6825] [client ::1:45002] PHP Deprecated: Non-static method PKPApplication::defineExposedConstant() should not be called statically in /var/www/html/rel/lib/pkp/classes/core/PKPApplication.inc.php on line 545
[Thu Jan 05 13:25:32.681061 2017] [:error] [pid 6825] [client ::1:45002] PHP Deprecated: Non-static method PKPApplication::getExposedConstants() should not be called statically in /var/www/html/rel/lib/pkp/classes/core/PKPApplication.inc.php on line 513
[Thu Jan 05 13:25:32.697608 2017] [:error] [pid 6825] [client ::1:45002] PHP Fatal error: Cannot use ‘String’ as class name as it is reserved in /var/www/html/rel/lib/pkp/classes/core/String.inc.php on line 57

Installation of ojs 3.X was right, I didn’t get that error
What can I do?

See: