The time to handle unexpected issues at your conference is... before they happen. Write down a list of anything that can go wrong at every segment of the conference, and have a contingency plan for each. Have extra batteries on hand for all of your mics. Have a plan for what to do if things are running behind schedule (or ahead). As a corporate entertainer with a specialty in conferences, I don't just plan for my alloted time on stage - I'm ready to jump into action at a moments notice if there is a food delay, etc. I can jump on stage and entertain everyone / lead them in an ad-hoc team building excercise, etc. Clients love it, and it turns a big minus into a big plus.

Assess the situation and identify the cause. Communicate proactively by informing attendees. Be transparent and honest about the situation. If the delay is significant, explore alternative food options. Apologize and express sincere apologies for the inconvenience. Then provide reassurance that the situation is being addressed and that their comfort is a priority. Maintain a positive attitude and stay calm and collected. A positive demeanor can help alleviate frustration among attendees.