Hi Bozana,
Thank you for pointing to the error log. The problem seems to be the Citation Style Language plugin, probably in combination with PHP 5.5. The crucial error log is:
PHP Fatal error: Arrays are not allowed in class constants in <...>/plugins/generic/citationStyleLanguage/lib/vendor/seboettg/citeproc-php/src/Seboettg/CiteProc/Util/StringHelper.php on line 27, referer: https://<...>/index.php/<...>/issue/view/1
When I deactivate the Citation Style Language plugin the landing page is displayed as expected.
I found some discussions around this issue, especially this one:
https://forum.pkp.sfu.ca/t/ojs-3-1-0-issue-with-citation-style-language-plugin
The advices was to update to PHP 5.6 (we actually have PHP 5.5.9 running).
@Bozana: Do you know if upgrading to PHP 5.6 actually solves this issue?
Thanks,
Armin