OJS 3.1.0.1 - Can't upload file in Subbmision stage as JM

When we are in Submission we can’t upload file as Journal Manager (system doesn’t allow continue button)
1

After refreshing page file appears to be there but when we try to download it server give us error 500.

PHP Error log:

[Mon Feb 19 14:50:49.136984 2018] [fcgid:warn] [pid 9485] [client 192.168.131.1:61765] mod_fcgid: stderr: FileApiHandler: File /var/www/clients/client0/web7/private/files/journals/6//articles/2017/submission/2017-1-4054-1-2-20180219.docx does not exist or is not readable!, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1
[Mon Feb 19 14:50:49.136991 2018] [fcgid:warn] [pid 9485] [client 192.168.131.1:61765] mod_fcgid: stderr: ojs2: 500 Internal Server Error, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1
[Mon Feb 19 14:50:54.477612 2018] [fcgid:warn] [pid 8905] [client 192.168.131.1:62042] mod_fcgid: stderr: PHP Notice:  Undefined offset: 0 in /var/www/clients/client0/web7/web/lib/pkp/classes/context/Context.inc.php on line 273, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/submissions
[Mon Feb 19 14:50:54.477649 2018] [fcgid:warn] [pid 8905] [client 192.168.131.1:62042] mod_fcgid: stderr: PHP Notice:  Undefined offset: 0 in /var/www/clients/client0/web7/web/lib/pkp/classes/context/Context.inc.php on line 273, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/submissions
[Mon Feb 19 14:50:54.842848 2018] [fcgid:warn] [pid 8905] [client 192.168.131.1:62042] mod_fcgid: stderr: PHP Notice:  Undefined offset: 0 in /var/www/clients/client0/web7/web/lib/pkp/classes/context/Context.inc.php on line 273, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1
[Mon Feb 19 14:50:54.842869 2018] [fcgid:warn] [pid 8905] [client 192.168.131.1:62042] mod_fcgid: stderr: PHP Notice:  Undefined offset: 0 in /var/www/clients/client0/web7/web/lib/pkp/classes/context/Context.inc.php on line 273, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1
[Mon Feb 19 14:51:08.157134 2018] [fcgid:warn] [pid 8865] [client 192.168.131.1:62179] mod_fcgid: stderr: PHP Notice:  Undefined offset: 0 in /var/www/clients/client0/web7/web/lib/pkp/classes/context/Context.inc.php on line 206, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1
[Mon Feb 19 14:51:08.157141 2018] [fcgid:warn] [pid 8865] [client 192.168.131.1:62179] mod_fcgid: stderr: ojs2: Unknown locale component , referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1
[Mon Feb 19 14:51:20.335439 2018] [fcgid:warn] [pid 8905] [client 192.168.131.1:62262] mod_fcgid: stderr: PHP Notice:  Undefined offset: 0 in /var/www/clients/client0/web7/web/lib/pkp/classes/context/Context.inc.php on line 273, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1
[Mon Feb 19 14:52:29.652125 2018] [fcgid:warn] [pid 8905] [client 192.168.131.1:62744] mod_fcgid: stderr: PHP Notice:  Undefined offset: 0 in /var/www/clients/client0/web7/web/lib/pkp/classes/context/Context.inc.php on line 273, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/admin
[Mon Feb 19 14:52:29.652152 2018] [fcgid:warn] [pid 8905] [client 192.168.131.1:62744] mod_fcgid: stderr: PHP Notice:  unserialize(): Error at offset 15 of 201 bytes in /var/www/clients/client0/web7/web/lib/pkp/classes/db/DAO.inc.php on line 352, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/admin
[Mon Feb 19 14:52:29.652156 2018] [fcgid:warn] [pid 8905] [client 192.168.131.1:62744] mod_fcgid: stderr: PHP Notice:  unserialize(): Error at offset 81 of 219 bytes in /var/www/clients/client0/web7/web/lib/pkp/classes/db/DAO.inc.php on line 352, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/admin
[Mon Feb 19 14:52:29.932941 2018] [fcgid:warn] [pid 8905] [client 192.168.131.1:62744] mod_fcgid: stderr: PHP Notice:  Undefined offset: 0 in /var/www/clients/client0/web7/web/lib/pkp/classes/context/Context.inc.php on line 273, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/admin
[Mon Feb 19 14:52:56.059168 2018] [fcgid:warn] [pid 9364] [client 192.168.131.1:62971] mod_fcgid: stderr: PHP Notice:  Undefined offset: 0 in /var/www/clients/client0/web7/web/lib/pkp/classes/context/Context.inc.php on line 206, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1
[Mon Feb 19 14:52:58.968499 2018] [fcgid:warn] [pid 9687] [client 192.168.131.1:63039] mod_fcgid: stderr: FileApiHandler: File /var/www/clients/client0/web7/private/files/journals/6//articles/2017/submission/2017-1-4055-1-2-20180219.xml does not exist or is not readable!, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1
[Mon Feb 19 14:52:58.968575 2018] [fcgid:warn] [pid 9687] [client 192.168.131.1:63039] mod_fcgid: stderr: ojs2: 500 Internal Server Error, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1
[Mon Feb 19 14:53:00.293946 2018] [fcgid:warn] [pid 9364] [client 192.168.131.1:62971] mod_fcgid: stderr: PHP Notice:  Undefined offset: 0 in /var/www/clients/client0/web7/web/lib/pkp/classes/context/Context.inc.php on line 273, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/submissions
[Mon Feb 19 14:55:04.173807 2018] [fcgid:warn] [pid 9488] [client 192.168.131.1:64046] mod_fcgid: stderr: PHP Notice:  Undefined offset: 0 in /var/www/clients/client0/web7/web/lib/pkp/classes/context/Context.inc.php on line 206, referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1
[Mon Feb 19 14:55:04.173814 2018] [fcgid:warn] [pid 9488] [client 192.168.131.1:64046] mod_fcgid: stderr: ojs2: Unknown locale component , referer: http://godisnjak.ff.uns.ac.rs/index.php/gff/workflow/index/2017/1

On the other hand, authors can complete submission and upload files without any problems.