MyBB Community Forums

If i upgrade mybb should i get anytype of error to my plugins ? or to my theme

As long as you are already on the 1.8. series you should not experience any dramatic changes in functionality. However, be sure to run the upgrade script.

See: http://docs.mybb.com/1.8/install/upgrade/

If you upgrade from 1.6 to 1.8 then you need to make sure your plugins and themes has been updated to support 1.8. Chances are, they won't.

1.8 updates (1.8.4 -> 1.8.5 for example) should be fine.