This error message can pop up in multiple places within the system.
In a simple term, it means that the data entered is too long for the database field so would be cut off. In this scenario the system will not let you save the entry.
The most common places seen are when creating booking templates:
The solution to this error is to shorten the description entered.
If you are unsure which field is causing the error please contact the support team and send over the SQL error shown further down in the error box:
The support team can then run this SQL error manually to determine which field is the problem if it's not stated in the error message.