99.9999% probability you are trying to use the object you just deleted.
If you call deleteLater on an object you then have to recreate it (e.g. with new) before using it or trying to delete it again

@mrjj well, thanks.
I've tried to add #include <sqltypes.h> just in case, and voilà, now there are errors(C2065, C3861) inside Qt(drivers\odbc\qsql_odbc.cpp).

Don't know if it's better, but still something.