Not found on Accelerator

I am getting an error that says {CalDav} Sync of MY EMAIL ADDRESS failed due to error: MY EMAIL ADDRESS (Not found on Accelerator). I’m not sure what this means and how I fix it.

Hi, can you please make a screenshot of the error?
What version of eM Client are you currently using on your computer? What mail/calendar service are you using with eM Client?

Thank you,
Paul.