We had to replace several speakers because they either didn’t get visas or required sponsorship for their travel. While the latter one was no one fault, the visa situation was extremely annoying. People applied for visas way in advance, and they should not have wait for many months. I am still mad that it happened!
Additionally, there were several mini -calamities, like there were three speakers who forgot to register, and there was one speaker who’s flight was delayed multiple times, so he ended up arriving to the venue nine minutes before his talk! Our head of the CfP Committee was pacing the hallway with the phone in her hand watching for the speaker’s messages. I ran up to the registration desk and checked him in, so that he could have his badge ready. He made it!
I should also mention that our keynote was at risk until days before the event, but this was also happily resolved.
And the program was the best I could imagine!