Header error in error_log

Hi,

I see this error in my error_log file realted to anspress functions. How can it be solved?

[19-Feb-2016 14:37:45 UTC] PHP Warning:  Illegal string offset 'file' in /home/kin0co/public_html/wp-content/plugins/anspress-question-answer/includes/class-user.php on line 482
[19-Feb-2016 14:37:45 UTC] PHP Warning:  Illegal string offset 'small_file' in /home/kin0co/public_html/wp-content/plugins/anspress-question-answer/includes/class-user.php on line 486
[19-Feb-2016 14:37:45 UTC] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/kin0co/public_html/wp-content/plugins/anspress-question-answer/includes/class-user.php:482) in /home/kin0co/public_html/wp-content/plugins/anspress-question-answer/includes/functions.php on line 869
[19-Feb-2016 14:37:45 UTC] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/kin0co/public_html/wp-content/plugins/anspress-question-answer/includes/class-user.php:482) in /home/kin0co/public_html/wp-content/plugins/anspress-question-answer/includes/functions.php on line 872
[19-Feb-2016 14:37:45 UTC] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/kin0co/public_html/wp-content/plugins/anspress-question-answer/includes/class-user.php:482) in /home/kin0co/public_html/wp-content/plugins/anspress-question-answer/includes/functions.php on line 877