Austria is actually not suspecting any fraud. About 100 000 postal ballots were counted not fully following the protocol demanded by law, and the elections were

Austria is actually not suspecting any fraud. About 100 000 postal ballots were counted not fully following the protocol demanded by law, and the elections were decided by a difference of about 30 000 voted. They have no evidence or suspicion of actual fraud, but the legitimacy of the result can still be questioned, so they decided to re-run the elections.