Ossharareru combines two honorific forms of the verb “to say”: the respectful verb ossharu and the respectful ending -rareru. It is called nijū keigo, double honorific language. A business etiquette guide says that piling up honorific forms creates this mistake, and does not make speech more polite.
The guide corrects Ashita no kaigi wa nanji kara to ossharare mashita ka? to osshaimashita ka? “What time did you say tomorrow’s meeting starts?”