I work on BO BI 4.1 SP4 (version 126.96.36.1997) and I found a note (2043161) that could fix my problem ("An Internal error occurred while calling 'opendocument API . (Error:ERR_WIS_30270)( WIS 30270)").
This note give the patch 5 as a solution but for SP3.
So I looked in SP4 and I didn't find the equivalent.
Do you know in which SP / patch I could get it ?