Server Administration > Item Type Attributes > Customizing Error Messages for Constraints > Customizing Constraint Error Messages
  
Customizing Constraint Error Messages
You customize the error message by setting the specified tokens and adding plain text to create the complete message content.
The following tokens are available for customizing constraint error messages:
{SourceField} is replaced by a list of source fields of the constraint.
{SourceValue} is replaced by the source field value of the constraint.
{ConstrainedField} is replaced by the name of the constrained field.
{ConstrainedValue} is replaced by the allowed values of the constrained field.
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When defining the message for an empty mandatory field, you can only select the {ConstrainedField} token.
If you save an empty error message field, the default message is displayed to users (see “Default Constraint Error Messages”.
Example: Customized Mandatory Field Error Message
Using a {ConstrainedField} token, you can specify that the constrained field must have a value of Project:
The “{ConstrainedField}” field is mandatory. You must enter a value for “{ConstrainedField}” before you can save this item.
This translates to:
The “Project” field is mandatory. You must enter a value for “Project” before you can save this item.
To customize a constraint error message in the GUI