If an error occurs during the saving of a registration then an e-mail will automatically be sent to you with the description of the error. 

Possible causes for errors include:

• E-mail Sending Errors
  • No E-mail template selected
  • Invalid SMTP configuration
  • Missing or invalid recipient e-mail address
  • Invalid template configuration
  • Mail Server errors
• After-Save actions
  • Attempting to use a print action with no printer connected
• Online Payment Errors
  • Invalid or missing DIY Payment gateway credentials

The content of the e-mail should indicate the cause of the error, if you do not understand what is causing the error you can contact support@raceresult.com

Some common E-mail SMTP errors are explained here.

Note:
The ID listed in the context is the ID of the participant whose registration triggered the error. Quickly identify the participant in question by using the participants view filter, for example with the expression [ID]=123.