Erro fórum ipb

Boa tarde pessoal, gostaria de saber se alguém sabe como resolver esse erro.

Warning: Illegal string offset 'mid' in /home//public_html/forum/admin/applications/forums/sources/classes/post/classPostForms.php on line 841

Warning: Cannot modify header information - headers already sent by (output started at /home//public_html/forum/admin/applications/forums/sources/classes/post/classPostForms.php:841) in /home//public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 114

Warning: Cannot modify header information - headers already sent by (output started at /home//public_html/forum/admin/applications/forums/sources/classes/post/classPostForms.php:841) in /home//public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 127

Warning: Cannot modify header information - headers already sent by (output started at /home//public_html/forum/admin/applications/forums/sources/classes/post/classPostForms.php:841) in /home//public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 136

Warning: Cannot modify header information - headers already sent by (output started at /home//public_html/forum/admin/applications/forums/sources/classes/post/classPostForms.php:841) in /home//public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 137

Warning: Cannot modify header information - headers already sent by (output started at /home//public_html/forum/admin/applications/forums/sources/classes/post/classPostForms.php:841) in /home//public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 141

esse erro sempre aparece na hora que cria em criar novo tópico.

OBS: Se grupo no fórum tive marcado como moderador não aparece esse erro.

Olá, entendo que esse tópico é antigo porém, caso alguém tiver a mesma dúvida, esse problema ocorre quando o CHMOD não está configurado corretamente.