[Security] Why this happened in mybb?

[uchchash]

SQL Error:
1267 - Illegal mix of collations (latin1_general_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE) for operation '='
Query:
SELECT p.pid FROM mybb_posts p WHERE p.uid='1' AND p.fid='22' AND p.subject='' AND p.message=' why this show me whn i had posted?

[Leefish]

Are you using any plugins? Try disabling plugins in ACP and then try to post.

[uchchash]

Have tow plugins gomobile and recent threads. What to do?